Make "Get started with Builds" Help Page link work properly

`help_page_path('ci/quick_start', 'README')` causes a link to `https://gitlab.com/help/ci%2Fquick_start/README` which in turn breaks every relative link on the page. This remedies the problem.

That said, this is probably a horrible way of fixing this issue, *but* it does work. I can’t find much information on linking this deeply with Rails routes.

If anyone has suggestions as to a better way of handling this, I'll gladly take them. I tried a few different things, but none of them really worked.

Resolves #14872.

cc: @axil @rspeicher @elstamey

See merge request !3561

Optimize cross ref system notes check

## What does this MR do?

This MR optimizes system note visibility checking by memoizing the visible reference count, reducing the overhead of calling `Note#cross_reference_not_visible_for?`.

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

Note that since a cross reference message contains, "Mentioned in XYZ", we EXPECT that there is at least one reference. That's why using the ref count > 0 works. 

## Why was this MR needed?

The previous implementation relied on `Note#cross_reference_not_visible_for?`, which essentially tries to render all the Markdown references in a system note
and only displays the note if the user can see the referring project. But this duplicated the work that Banzai::NotesRenderer was doing already. This shaves about 0.8 s
from the load time from https://gitlab.com/gitlab-com/operations/issues/42.

## What are the relevant issue numbers?

#19273

## Screenshots (if relevant)

## 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
  - [x] Added for this feature/bug
  - [x] 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 !5070

Added day name to contributions calendar

## What does this MR do?

Adds the day name text into the contributions calendar tooltip.

## What are the relevant issue numbers?

Closes #19367 

## Screenshots (if relevant)

![Screen_Shot_2016-07-04_at_12.38.52](/uploads/edf6ac3454d479a345aee638875b7713/Screen_Shot_2016-07-04_at_12.38.52.png)

See merge request !5065

have been fully redacted and contain cross-project references.

The previous implementation relied on Note#cross_reference_not_visible_for?,
which essentially tries to render all the Markdown references in a system note
and only displays the note if the user can see the referring project. But this
duplicated the work that Banzai::NotesRenderer was doing already. Instead, for
each note we render, we memoize the number of visible user references and
use it later if it is available.

Improves #19273

Remove pinTo from Flash

## What does this MR do?

- replace `pinTo` of `Flash` by `parent` parameter in constructor
- move positioning of layout containers from CoffeeScript to layout files
- adjust styling of inline flash messages

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

- display of flash messages in general

## Why was this MR needed?

- allow finding and positioning flash message containers within layout files
- allow adding different CSS classes to flash containers within layout files (necessary for fixing #18908)
- allow multiple flash messages to be displayed at different places at the same time
- make inline flash messages look nicer

## What are the relevant issue numbers?

closes #18908, closes part of #18897

## Screenshots

### Inline flash message (before)
![before](/uploads/c5b3cc05140eaeb9d14e481fa506ebbf/before.png)
![before-mobile](/uploads/004b1f2b9510bd97f4f8a7a6e56f17ef/before-mobile.png)

### Inline flash message (after)
![inline-flash-message](/uploads/fe2a23b63623612b696d529e81fa459e/inline-flash-message.png)
![inline-flash-mobile](/uploads/6207604acfebcf7402d77d5638c89ca8/inline-flash-mobile.png)

### Other flash messages (after)

![flash-message-issue](/uploads/d7e12bd0da68cfa333471ed102428cec/flash-message-issue.png)
---
![flash-new-project](/uploads/3465967dba83296068f154f149d26f64/flash-new-project.png)
---
![flash-sign-in](/uploads/4a5b317d5a369034f43343031607a0c2/flash-sign-in.png)
---
![flash-file-comment](/uploads/488a1119374be7e2173c0a590cfd8821/flash-file-comment.png)
---
![flash-fork](/uploads/f41964e8b910801e03eef3d7649e5009/flash-fork.png)
---
![flash-update-profile](/uploads/9fd972d6c6609fbbf86afcd99d343b5f/flash-update-profile.png)
---

### This is possible now

![flashs-everywhere](/uploads/07f425534511fb4ecaa1d7e2a9870787/flashs-everywhere.png)


See merge request !4854

[ci skip]

Clean up coffeescript files imported from GitLab CI

## What does this MR do?

This MR cleans up CoffeeScript files imported from GitLab CI along with a strategy #19159. Some files should have been removed in !1987.

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

While I think the `Build` module should be named as `Build`, not `CiBuild` in the JavaScript namespace, please check if it should.

## Why was this MR needed?

Removing unused coffeescript files reduces time to build JS and so time to transfer even in production. The fewer files, the better, too.

## What are the relevant issue numbers?

Closes #19159

## Screenshots (if relevant)

n/a

## Does this MR meet the acceptance criteria?

- [skipped] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [skipped] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [skipped] API support added
- Tests
  - [skipped] Added for this feature/bug
  - [x] 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 !4925

This is probably a horrible way of fixing this issue, but it does work.
I can’t find much information on linking this deeply with Rails routes.

Resolves #14872.

Fix problems with events under notes importing GitLab projects

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/19588

See merge request !5154

Correctly shows close button on merge requests

Closes #19403 

See merge request !5036

Allow SentNotification#position to be set as string or hash

Fixes https://sentry.gitlap.com/gitlab/staginggitlabcom/issues/8491/

See merge request !5189

Single file diffs

Closes #14103. Related (not part of this MR): #19553.

This adds a `diff_for_path` action to each place we render diffs (commit, compare, new MR, existing MR) which renders the diff for a single path. The action is always available with the same params as the 'parent' action, to make it simpler to generate the URIs.

If a diff is bigger than 10 KB, it will be collapsed by default and have a data attribute added. You can then click the message or the filename to expand that diff. For expanded files, you can collapse and expand them, but they won't make any AJAX requests.

![Expand_and_collapse_diffs](/uploads/a4072029085082b85c47006f67ac531c/Expand_and_collapse_diffs.gif)

See merge request !4990

entities: remove :description from MergeRequest

## What does this MR do?

Removes a duplicate `description` key from API JSON objects.

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

No.

## Why was this MR needed?

`description` is already exported via `ProjectEntity` and doesn't need to be listed in `MergeRequest` as well.

## What are the relevant issue numbers?

N/A

## Screenshots (if relevant)

N/A

## 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 !5099

Use Gitlab-Workhorse-Send-Data to send entry

## What does this MR do?

Use Gitlab-Workhorse-Send-Data to send entry:

Closes #19224, Closes #19128

Also requires this MR to work:
https://gitlab.com/gitlab-org/gitlab-workhorse/merge_requests/53

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

Do we have a test for this?

## Why was this MR needed?

This way gitlab-workhorse does not have to call any API.

See merge request !5094

Remove "not released" status from documentation

[ci skip]

See merge request !5024

squashed - refactor to cope with sub sub N relations probably using the sub_relations method recursively.

Add side shadow for unpinned sidebar



See merge request !5167

It is already part of ProjectEntity.

Make color that highligh today issues more lightweight



See merge request !5168

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5094#note_12987385

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5094#note_12984211

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

MySQL's text column isn't big enough for the diffs in the
expand-collapse-diffs branch.

Fix typo in factory for projects.rb

## 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 !5100

Add reminder to not paste private SSH keys

## What does this MR do?

Just got the "How would you make GitLab better?" mail and thought that I could follow it.

This commit adds a short reminder to not paste the private part of an SSH key to the form where one can add SSH keys to one's account. I think that's an useful message, both for people who aren't that experienced yet and for people who are sleep-deprived. :-)

I decided to just list the most common key type, `ssh-rsa`. The full list of key types in the [CVS repository of OpenSSH](http://cvsweb.openbsd.org/cgi-bin/cvsweb/~checkout~/src/usr.bin/ssh/sshkey.c?rev=HEAD&content-type=text/plain) contains some types which I'd regard as a bit obscure. Mentioning all of those types would probably clutter the form too much. We could think about whether to list what is probably the second most common key type, namely `ssh-dss`. But note that this key type [seems to be deprecated](https://security.stackexchange.com/questions/5096/rsa-vs-dsa-for-ssh-authentication-keys).

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

I didn't actually test this one-line change.

## Why was this MR needed?

It's not, strictly speaking, needed, but could be considered a nice addition.

See merge request !4399

Remove slow migration and add fix to sanitize errors

Getting rid of the slow migration and preventing the Error to occur

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/19608

See merge request !5176

Run bundle install and update Gemfile.lock

!5078 didn't update the `Gemfile.lock` even though it added some restrictions on gem versions, this fixes that.

cc: @rymai 

See merge request !5159