Fix Error 500 when attempting to sort merge requests by weight

Fixes #673

See merge request !477

Fixes #673

Fix JenkinsService test button

When clicking the "Test" button on the JenkinsCI Service, the following error occurs:

```
We tried to send a request to the provided URL but an error occurred: undefined method `message' for [200, ""]:Array 
```

!374 changed the implementation to call the `WebHook`, which returns [status, message], instead of the return value of `HTTParty#post`.

Closes #637

See merge request !476

File Lock

Fixes https://gitlab.com/gitlab-org/gitlab-ee/issues/497

- [x] Data layer(tables, models, migrations)
- [x] Checks on git push
- [x] Author should be able to push if one owns the lock
- [x] Path matcher with tokenizer and memoization
- [x] Show lock status icons by files and folders
- [x] UI: mockup buttons for locking files, folders
- [x] UI: Locking files
- [x] UI: Locking folders
- [x] Permissions check everywhere
- [x] Add page to list all locked files/dirs to get overview in case people forget to unlock
- [x] Refactor `lock_file_button` and `lock_file_link`
- [x] Testing Git LFS
- [x] Get rid of code duplication in pre-receive hook
- [x] Test case: I want to unlock file if I'm a developer and I'm not an author of lock
- [x] Make it EE option
- [x] Specs and spinach
- [x] TODOs in the code

Can be moved to the next iteration:
- [ ] Duplicate lock checks in the service since pre-receive hook does not work for UI (according to Douwe)
- [ ] timeago in the lock icon tooltip. It's not working out of the box.
- [ ] Ajax load bar on click "Lock/Unlock" in the file tree
- [ ] Nested locking UI. If we look at file and it's locked because of parent we should show it in tooltip. 


**Screenshots**

![joxi_screenshot_1466188707474](/uploads/623e65c9a246b07c9786fd8babdb2dd8/joxi_screenshot_1466188707474.png)![joxi_screenshot_1466188735083](/uploads/4588eff352ee544de5bb5727d501a2cc/joxi_screenshot_1466188735083.png)![joxi_screenshot_1466188758950](/uploads/dee7b342c7825a79ed1629535eced5ed/joxi_screenshot_1466188758950.png)


Related info:
Douwe wrote:
```For a next iteration, we need to think about nested locking more. If user A has locked lib/, user B shouldn't be able to lock lib/foo.rb since that falls under lib/. Similarly, if user A has locked lib/foo.rb, user B shouldn't be able to lock lib/, because part of that directory is locked by someone else already.```

See merge request !440

Closes #637

Show flash notice when Git Hooks are updated successfully

Fixes #320

See merge request !475

Set GL_ID in MergeRequests::RebaseService

We missed this in 6280bcc0 I think.

See merge request !472

ES: Project members with guest role can't access confidential issues

## What does this MR do?

Restrict access to confidential issues to team members with at least Reporter access when performing search using Elasticsearch.

Allow users to create confidential issues in private projects, and exclude access to them to project members with `Guest` role.

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

The query generated in the `Elastic::NotesSearch.elastic_search` method.

## Why was this MR needed?

Confidential issues should only be visible to team members with at least Reporter access.

## What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/issues/14787

## Screenshots (if relevant)

Not relevant.

See merge request !471

MergeRequest#commits.last is actually first_commit

Using a method would be less confusing.

This was discovered in the process of figuring out https://gitlab.com/gitlab-org/gitlab-ee/issues/260

/cc @DouweM 

See merge request !453

Projects without import_url cannot be mirrors

See merge request !463

Update schema (and CE upstream with the fix)



See merge request !469

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

ES settings in the ApplicationSetting



See merge request !359

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

Update CHANGELOG-EE

[ci skip]

See merge request !468

Fix emoji block selector.

Fixes #18465 and #18577

See merge request !4604

[ci skip]

[ci skip]

[ci skip]

[ci skip]

[ci skip]