Turn Group#owners into a has_many association

## What does this MR do?

This turns the regular method `Group#owners` into a `has_many` association.

## Are there points in the code the reviewer needs to double check?

As far as I can tell there's no way to do this without using an intermediate association, but perhaps I'm missing something. The reason an intermediate association is needed is because the supplied Proc is applied to the _final_ association (the one returning users), this means that when using a single `has_many` you can't filter out any intermediate rows (e.g. group members).

## Why was this MR needed?

This code being a regular method would prevent eager loading of the owners of a Group, turning it into a `has_many` association resolves this problem. This was discovered in !4410.

## What are the relevant issue numbers?

None.

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] ~~[Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- [x] ~~API support added~~
- [ ] Tests
  - [x] Added for this feature/bug
  - [ ] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4676

Make project_id nullable

## What does this MR do?
Fixes the broken migration which is not in sync with `db/schema.rb`.

It's to solve https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/469.


See merge request !4701

This allows the owners to be eager loaded where needed.

Update migration_style_guide.md with new details

See merge request !4693

Hide the Todo button in the collapsed issuable sidebar.

## What does this MR do?

Fixes a bug where the "Add Todo" button was displayed in the collapsed sidebar.

## Are there points in the code the reviewer needs to double check?

This shouldn't remove any other elements from the collapsed sidebar.

## What are the relevant issue numbers?

None

## Screenshots (if relevant)

Before:

![Screen_Shot_2016-06-15_at_11.41.46_AM](/uploads/27a1ace58cf8c44ad96accd3d0b32f11/Screen_Shot_2016-06-15_at_11.41.46_AM.png)

After:

![Screen_Shot_2016-06-15_at_11.40.53_AM](/uploads/91a8585680fc482682d0efafdba4d599/Screen_Shot_2016-06-15_at_11.40.53_AM.png)

See merge request !4686

Fix long commit message scroll issue.

Fixes horizontal scrollbar for long commit description.

## Before
![before_](/uploads/d261e26044d8ab451bc7768b16316253/before_.png)

## After
![after](/uploads/f27227a77d25d80b797e3ffc916d1957/after.png)

See merge request !4643

Show categorised search queries in the search autocomplete

Fixes #5885 

It works in 3 categories, Dashboard, Groups and Project.

## Dashboard context
![for-dashboard](/uploads/3a59f6ec008a972495597c8f2691c385/for-dashboard.png)

## Group context
![for-group](/uploads/f7aa413d56330a1d9b2e5562f95badf7/for-group.png)

## Project context
![for-project](/uploads/dabe04cf8758a056cf7b03da001ffd91/for-project.png)


## Screencast
![category-search-dropdown](/uploads/4d9513dcd6ccb6e24adefdf65f9bc778/category-search-dropdown.gif)



See merge request !4499

# Conflicts:
#	app/assets/javascripts/lib/common_utils.js.coffee

Toggle whitespace button for compare page

## What does this MR do?

Adds whitespace button to compare branches page.

## Are there points in the code the reviewer needs to double check?

Ruby code.

## Why was this MR needed?

Compare branches UX

## What are the relevant issue numbers?

Closes #17881.

## Screenshots (if relevant)

![Screen_Shot_2016-06-09_at_18.39.48](/uploads/8995a7bc8bea7fa3ff19446ebe49fb88/Screen_Shot_2016-06-09_at_18.39.48.png)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- [ ] Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4569

Fix emoji block selector.

Fixes #18465 and #18577

See merge request !4604

Update CHANGELOG

[ci skip]

See merge request !4695

Revert "Merge branch '18047-event-item-links-dont-look-like-links' into 'master'"

## What does this MR do?

## Are there points in the code the reviewer needs to double check?

## Why was this MR needed?

## What are the relevant issue numbers?

## Screenshots (if relevant)

## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- [ ] Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4692

[ci skip]

[skip]

[ci skip]

[ci skip]

[ci skip]

[ci skip]

This reverts merge request !4544

Replace raphael-rails with raphael.js and split it from the rest of the JS

## What does this MR do?

Removes raphael.js and its related libraries from the default JS bundle.

It also removes raphael-rails because the gem is unmaintained and – for whatever reason – didn't want to cooperate with the way I was trying to require it.

This brings the default (compressed and minified) application.js from 354KB after the d3 MR (!4394) down to 324KB.

## Are there points in the code the reviewer needs to double check?

That tests pass and that there aren't errors on any pages (especially the Network page).

## Why was this MR needed?

It's only used on the Network page and was using way too much bandwidth for just one page.

## What are the relevant issue numbers?

#14372 #13165 

Follow-up to !4394 and !4516.

cc: @jschatz1 

See merge request !4519

Updated '.event-item a' color

## What does this MR do?

Changes the color of `.event-item` links.

## Are there points in the code the reviewer needs to double check?

Did you want this restricted only to the activity page or anywhere showing `.event-item`'s?

## Why was this MR needed?

UX

## What are the relevant issue numbers?

Closes #18047.

## Screenshots (if relevant)

![Screen_Shot_2016-06-08_at_20.07.54](/uploads/9670fbeb6fac7a334a83e11ffc05148c/Screen_Shot_2016-06-08_at_20.07.54.png)

See merge request !4544

added hover state to top nav links

## What does this MR do?

Adds hover state to top nav links.

## Are there points in the code the reviewer needs to double check?

Ney.

## Why was this MR needed?

UX.

## What are the relevant issue numbers?

Closes #18301.

## Screenshots (if relevant)

![Screen_Shot_2016-06-07_at_23.23.45](/uploads/dac8ed99eca99fbcccbd98028e947ee1/Screen_Shot_2016-06-07_at_23.23.45.png)

See merge request !4521

Due date can be removed from milestones

## What does this MR do?

Adds a button to milestone form to allow user to remove due date 

## What are the relevant issue numbers?

Closes #15063 

## Screenshots (if relevant)

![Screen_Shot_2016-06-02_at_08.32.03](/uploads/8bd4446abde745dd5b1e140a887ec694/Screen_Shot_2016-06-02_at_08.32.03.png)

See merge request !4428

Add shortcut to copy file content hash link

## What does this MR do?

* Allows for multiple shortcut handlers to be initialised
* Adds `y` shortcut to file pages to copy permalink URL.

## Are there points in the code the reviewer needs to double check?

Ney.

## Why was this MR needed?

UX

## What are the relevant issue numbers?

Closes #14470.

## Screenshots (if relevant)

![y-shortcut](/uploads/b81feb26d8e0d7d4996c4afa29f385d7/y-shortcut.gif)

See merge request !4496

#17804 Pipeline download artifacts text

## What does this MR do?

Improves wording to the pipeline artifacts download dropdown items.

## Are there points in the code the reviewer needs to double check?

I couldn't test this very easily, any tips?

## Why was this MR needed?

UX.

## What are the relevant issue numbers?

Closes #17804.

## Screenshots (if relevant)

See merge request !4391

New issue shortcut doesnt work on some pages

## What does this MR do?

1. Slightly tidies dispatcher switch case by utilising 'fall through' cases.
2. Adds shortcuts to project pipelines, milestones, builds and forks pages

## Are there points in the code the reviewer needs to double check?

I have a feeling that these may have been missed out of the case statements on purpose?

## Why was this MR needed?

Possible UX issue highlighted in #17929.

## What are the relevant issue numbers?

Closes #17929.

Closes #12616. (dup)

Closes #18123. (dup)

Closes #13688. (dup)

## Screenshots (if relevant)

See merge request !4393

Fixed issue with bold in issuable sidebar

## What does this MR do?

~~The sidebar contained both normal font weight & bold font weight, so this standardises them to bold.~~

After looking at the designs, i've updated the font weights & colors throughout the sidebar to correctly match them

## Screenshots (if relevant)

![Screen_Shot_2016-06-02_at_11.03.40](/uploads/0a3eb6a67ce5722c77f6adf2fe883017/Screen_Shot_2016-06-02_at_11.03.40.png)


See merge request !4398

Fixed notes action buttons on mobile

## What does this MR do?

Fixes the mobile screen size styling for notes action buttons. It ensures there is space between icons and forces parts of the notes header to stack

## Are there points in the code the reviewer needs to double check?

Stacking? 

## Why was this MR needed?

UX

## What are the relevant issue numbers?

Closes #18434.

## Screenshots (if relevant)

![Screen_Shot_2016-06-13_at_17.52.09](/uploads/18849fdfc4fcbf7b67fc66633bbac129/Screen_Shot_2016-06-13_at_17.52.09.png)

## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- [ ] Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4631

Fix clicking of find and download areas on file page

## What does this MR do?

Fixes the stacking context of the file page so the find and download areas can be clicked

## Are there points in the code the reviewer needs to double check?

Ney

## Why was this MR needed?

We wanna click them. :(

## What are the relevant issue numbers?

Closes #18340.

## Screenshots (if relevant)

![Screen_Shot_2016-06-09_at_18.46.05](/uploads/1650a2fb1b9119ad1e27badf31f49340/Screen_Shot_2016-06-09_at_18.46.05.png)

## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- [ ] Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4574

Updated commits UI

Closes #14633 

See merge request !4271

Improve usability for prioritized labels

## What does this MR do?
- Adds an icon next to prioritized label rows serving as a hint to the user that the labels can be sorted by dragging them.
- Adds description about prioritized labels.
- Restores empty message when removing all prioritized labels.

## Screenshots (if relevant)

![labels](/uploads/1da16c4c54a894fa45ccc47e3a5bdf7a/labels.gif)

Closes #18575 

See merge request !4652

New Project page improvements for mobile

## What does this MR do?

Redesigns the "Project path" fields on the New Project page.

## Are there points in the code the reviewer needs to double check?

Not that I know of, nothing I changed should break any other pages.

## Why was this MR needed?

The new project page was unusable on mobile because the project name text field didn't have enough space.

## What are the relevant issue numbers?

Fixes #18599.

## Screenshots (if relevant)

Before:

![Screen_Shot_2016-06-15_at_12.38.58_PM](/uploads/046a824b283e24266cabc9ea3dfb169c/Screen_Shot_2016-06-15_at_12.38.58_PM.png)

After:

![Screen_Shot_2016-06-15_at_12.37.19_PM](/uploads/6d01310192965b413bfedd9c8d2129f7/Screen_Shot_2016-06-15_at_12.37.19_PM.png)

![Screen_Shot_2016-06-15_at_12.37.28_PM](/uploads/3944a0f0ab04373ec92f7cafe90872df/Screen_Shot_2016-06-15_at_12.37.28_PM.png)

## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] Tests
  - [x] Added for this feature/bug
  - [ ] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

cc: @jschatz1 @dzaporozhets 

See merge request !4687

Pinned sidebar navigation option

## What does this MR do?

Gives the ability to pin the sidebar navigation. Pinning is only possible on screens with above `lg` which is `1200px` if not it reverts to being hidden by default.

## What are the relevant issue numbers?

Closes #18542 

## Screenshots (if relevant)

### Un-pinned

![Screen_Shot_2016-06-15_at_17.29.08](/uploads/82b7495df6ea46a2334a7c25d03b019b/Screen_Shot_2016-06-15_at_17.29.08.png)

### Pinned

![Screen_Shot_2016-06-15_at_17.29.41](/uploads/3eb381be807985d0a9583f000cb802f9/Screen_Shot_2016-06-15_at_17.29.41.png)

See merge request !4683

Update CHANGELOG for 8.8.5 release

[ci skip]

See merge request !4688

Fair usage of Shared Runners

## What does this MR do?

Introduces a fair usage scheduler for shared runners.

It tries to assign builds to shared runner from projects that have the lowest number of builds currently running on shared runners.

**Example 1**:
```
We have following builds in queue:
build 1 for project 1
build 2 for project 1
build 3 for project 1
build 4 for project 2
build 5 for project 2
build 6 for project 3

With the new algorithm we will assign builds in following order:
- We choose build 1, because project 1 doesn't run currently any builds and has the lowest build number from projects that doesn't run builds,
- We choose build 4, because project 2 doesn't run currently any builds and has the lowest build number from projects that doesn't run builds,
- We choose build 6, because project 3 doesn't run currently any builds and has the lowest build number from projects that doesn't run builds,
- We choose build 2, because project 1 as other it runs 1 build,
- We choose build 5, because project 2 runs 1 build, where project 1 runs 2 builds now,
- We choose build 3, because project 1 and runs 2 builds.
```

 
**Example 2**:
```
We have following builds in queue:
build 1 for project 1
build 2 for project 1
build 3 for project 1
build 4 for project 2
build 5 for project 2
build 6 for project 3

With the new algorithm we will assign builds in following order:
- We choose build 1, because project 1 doesn't run currently any builds and has the lowest build number from projects that doesn't run builds,
- We finish build 1,
- We choose build 2, because project 1 doesn't run currently any builds and has the lowest build number from projects that doesn't run builds,
- We choose build 4, because project 2 doesn't run currently any builds and has the lowest build number from projects that doesn't run builds,
- We finish build 4,
- We choose build 5, because project 2 doesn't run currently any builds and has the lowest build number from projects that doesn't run builds,
- We choose build 6, because project 3 doesn't run currently any builds,
- We choose build 3, because project 1, 2 and 3 runs exactly one build now,
```

## Why was this MR needed?

Currently, we are scheduling builds using FIFO. This is catastrophic if there are projects that create a 100-300 jobs, this basically eats most of available shared runners.

## Performance

All this logic is implemented with the help of SQL queries, because this is the fastest way to process 1k-2k pending builds in queue.
It's not the fastest SQL query, because it sorts based on number of running_builds, and this forces to calculate a number of running builds for all dependent projects. However, since we have one/two shared runners that asks every few seconds for builds this should have minimal impact on DB performance.

```
 explain analyze SELECT "ci_builds".* FROM "ci_builds" JOIN (SELECT "ci_builds"."gl_project_id", count(case when status = 'running' AND runner_id = (SELECT "ci_runners"."id" FROM "ci_runners" WHERE "ci_runners"."is_shared" = 't') then 1 end) as running_builds FROM "ci_builds" INNER JOIN "projects" ON "projects"."id" = "ci_builds"."gl_project_id" AND "projects"."pending_delete" = 'f' WHERE "ci_builds"."type" IN ('Ci::Build') AND "ci_builds"."status" IN ('running', 'pending') AND "projects"."builds_enabled" = 't' AND "projects"."shared_runners_enabled" = 't' GROUP BY "ci_builds"."gl_project_id") AS projects ON ci_builds.gl_project_id=projects.gl_project_id WHERE "ci_builds"."type" IN ('Ci::Build') AND "ci_builds"."status" = 'pending' AND "ci_builds"."runner_id" IS NULL  ORDER BY projects.running_builds ASC, ci_builds.id ASC;
                                                                                  QUERY PLAN                                                                        
           
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
-----------
 Sort  (cost=64777.28..64777.29 rows=1 width=1010) (actual time=301.794..302.535 rows=1537 loops=1)
   Sort Key: (count(CASE WHEN (((public.ci_builds.status)::text = 'running'::text) AND (public.ci_builds.runner_id = $0)) THEN 1 ELSE NULL::integer END)), public.ci
_builds.id
   Sort Method: quicksort  Memory: 1423kB
   ->  Nested Loop  (cost=63279.78..64777.27 rows=1 width=1010) (actual time=66.384..298.724 rows=1537 loops=1)
         ->  HashAggregate  (cost=63177.15..63177.30 rows=15 width=15) (actual time=65.641..65.851 rows=187 loops=1)
               InitPlan 1 (returns $0)
                 ->  Seq Scan on ci_runners  (cost=0.00..26963.66 rows=1 width=4) (actual time=1.145..34.381 rows=1 loops=1)
                       Filter: is_shared
                       Rows Removed by Filter: 6965
               ->  Nested Loop  (cost=0.00..36186.34 rows=2715 width=15) (actual time=0.065..29.717 rows=1710 loops=1)
                     ->  Index Scan using index_ci_builds_on_status on ci_builds  (cost=0.00..8913.95 rows=3577 width=15) (actual time=0.051..12.012 rows=2583 loops
=1)
                           Index Cond: ((status)::text = ANY ('{running,pending}'::text[]))
                           Filter: ((type)::text = 'Ci::Build'::text)
                           Rows Removed by Filter: 1219
                     ->  Index Scan using projects_pkey on projects  (cost=0.00..7.61 rows=1 width=4) (actual time=0.003..0.004 rows=1 loops=2583)
                           Index Cond: (id = public.ci_builds.gl_project_id)
                           Filter: ((NOT pending_delete) AND builds_enabled AND shared_runners_enabled)
                           Rows Removed by Filter: 0
         ->  Bitmap Heap Scan on ci_builds  (cost=102.63..106.64 rows=1 width=1002) (actual time=1.216..1.231 rows=8 loops=187)
               Recheck Cond: ((gl_project_id = public.ci_builds.gl_project_id) AND ((status)::text = 'pending'::text))
               Filter: ((runner_id IS NULL) AND ((type)::text = 'Ci::Build'::text))
               ->  BitmapAnd  (cost=102.63..102.63 rows=1 width=0) (actual time=1.201..1.201 rows=0 loops=187)
                     ->  Bitmap Index Scan on index_ci_builds_on_gl_project_id  (cost=0.00..10.52 rows=241 width=0) (actual time=0.406..0.406 rows=1944 loops=187)
                           Index Cond: (gl_project_id = public.ci_builds.gl_project_id)
                     ->  Bitmap Index Scan on index_ci_builds_on_status  (cost=0.00..91.78 rows=3089 width=0) (actual time=0.652..0.652 rows=3362 loops=187)
                           Index Cond: ((status)::text = 'pending'::text)
 Total runtime: 303.832 ms
```

## Specific runners

It doesn't affect the specific runners which still serve builds FIFO.

@stanhu @markpundsack @yorickpeterse What do you think?


See merge request !4634

[ci skip]