Refactor spam validation to a concern that can be easily reused and improve legibility in `SpamCheckService`

Rescue Rugged::OSError (lock exists) when creating references.

## What does this MR do?

Rescue an exception on concurrent scenarios. I was able to create a spec for this, because if you create the lock file before trying to create the reference the reference is created without a problem and the lock file is removed. So IMHO there is a race condition where more than one process is trying to create the same reference at the same time raising the exception, so I just added the patch without specs.

```ruby
    it "attempting to call keep_around when exists a lock does not fail" do
      ref = repository.send(:keep_around_ref_name, sample_commit.id)
      path = File.join(repository.path, ref)
      lock_path = "#{path}.lock"

      FileUtils.mkdir_p(path)
      File.open(lock_path, 'w') { |f| f.write('') }

      begin
        # No exception is raised because the lock file is removed at some point in the process
        repository.keep_around(sample_commit.id)
      ensure
        File.delete(path)
        File.delete(lock_path)
      end
    end
```

## Why was this MR needed?

## What are the relevant issue numbers?

Closes #20156

## 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
  - [ ] 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 !5497

Add branch or tag icon to ref in builds page

## What does this MR do?
Add branch or tag icon to ref in builds page

## Why was this MR needed?
It's currently missing but should be there

## What are the relevant issue numbers?
Closes #20139 

## Screenshots (if relevant)
<img src="/uploads/fb5c9a285a1ce95c0aa8dfa5e32c5d7d/Screen_Shot_2016-07-22_at_9.14.39_AM.png" width="400px">


See merge request !5434

Fix expand all diffs button in compare view

## What does this MR do?

Fix the expand all diffs button in compare view.

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

Don't think so.

## Why was this MR needed?

We can't reuse the existing value of the format parameter, because on
the merge request page that's 'json', so the link would go to a JSON
file. We can't set it to HTML, because that adds '.html' to the URL, which
breaks the compare view (and looks bad). Setting it to `nil` uses the
default format, which in all of these cases is HTML anyway.


## What are the relevant issue numbers?

Closes #20241.

See merge request !5500

Multiple trigger variables show in separate line

## What does this MR do?
Separate lines for multiple trigger variables

## Screenshot
![Zrzut_ekranu_2016-07-19_o_13.05.01](/uploads/a6f9ec842f65266ae38922b1e9d5ab84/Zrzut_ekranu_2016-07-19_o_13.05.01.png)

## What are the relevant issue numbers?
Closes #19006 

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] Add tests for multiple trigger variables view
  - [x] All builds are passing
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)

cc @ubudzisz @grzesiek @yorickpeterse @tmaczukin [@chastell](https://github.com/chastell) [@tomash](https://github.com/tomash)

See merge request !5357

We can't reuse the existing value of the format parameter, because on
the merge request page that's 'json', so the link would go to a JSON
file. We can't set it to HTML, because that adds '.html' the URL, which
breaks the compare view (and looks bad). Setting it to nil uses the
default format, which in all of these cases is HTML anyway.

Remove spec/features/projects/branches_spec.rb~HEAD file

## What does this MR do?
Remove unnecessary `spec/features/projects/branches_spec.rb~HEAD` file.

See merge request !5489

Ensure current user can retry a build before showing the 'Retry' button

## What does this MR do?

Fixes #20150.

## Does this MR meet the acceptance criteria?

- [x] [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)
- [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 !5476

Add support for using RequestStore within Sidekiq tasks via SIDEKIQ_REQUEST_STORE env variable

See merge request !5054

Add missing escape at line end

Documentation fix, pretty simple.

See merge request !5422

Signed-off-by: Rémy Coutable <remy@rymai.me>

Merge branch '20189-markdown-video-doesn-t-work-when-the-referenced-video-file-is-in-same-repo' into 'master'

Ensure relative paths for video are rewritten as we do for images

## What does this MR do?

This ensures that path to videos are rewritten as we do for images.

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

I've decided to add a new `Blob#video?` method for simplicity's sake but this should probably be added to `Gitlab::Git::Blob`.

## What are the relevant issue numbers?

Fixes #20189.

## Does this MR meet the acceptance criteria?

- [x] [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)
- [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 !5474

Signed-off-by: Rémy Coutable <remy@rymai.me>

Signed-off-by: Rémy Coutable <remy@rymai.me>

Disable MySQL foreign key checks before dropping all tables

Fixes #20237. Disables MySQL foreign key checks before dropping all tables in a restore. MySQL doesn't honor `CASCADE` without a special flag when the database/tables are created. In order to drop the tables we need to disable foreign key checks. After the drop, re-enable the key checks. 

WIP: Pending confirmation from customer that this fix works. 

See merge request !5472

This significantly reduces the DB churn in the PostReceive task when it
performs reference extraction.

See #18663

Added '*.js.es6 gitlab-language=javascript' to .gitattributes

## What does this MR do?

According to the branch name this adds the `sytanx` highlighting for `.js.es6` files, but this actually adds the `syntax` highlighting. 😆 

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

Is this the right place? 🏃 

## Why was this MR needed?

We need pretty ES6 diffs.

## What are the relevant issue numbers?

Flyin' solo 🛫 

## 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 !5486

Fix CI status icon link underline

## What does this MR do?

Changes the CSS so that CI status icon does not underline when it is hovered over.

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

Just need to make sure there aren't any side effects (`.ci-status-link` being used without an icon).
To my knowledge, every instance of `.ci-status-link` is tied to a `.ci-status-icon-{statusName}`.

## Why was this MR needed?

Resolves existing bug

## What are the relevant issue numbers?

#20103 

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [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 !5408

Fixed dropdown search field height in ie11

## What does this MR do?

Fixes the height of the search input in dropdown menus.

## What are the relevant issue numbers?

Closes #19684 

## Screenshots (if relevant)

![Screen_Shot_2016-07-11_at_11.49.52](/uploads/fc25bc3d2c3bbd195f30d1953dc12662/Screen_Shot_2016-07-11_at_11.49.52.png)

See merge request !5179

Reduced diff email CSS

## What does this MR do?

Reduces the amount of inline CSS on the diff emails.

## What are the relevant issue numbers?

#15178 

See merge request !5203

Add green outline to New Branch button

## What does this MR do?

Add green outline to New Branch button on issue page.

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

Nope.

## Why was this MR needed?

The button was not very visible.

## What are the relevant issue numbers?

fixes #18928 

## Screenshots

### Before

![before](/uploads/3bc890e249ef4c3852605a6350c05b9a/before.png)

### After

![after](/uploads/bc627902ffa7c7b4ab20ee7a269fa44f/after.png)

See merge request !5447

Add es6 gem

## What does this MR do?
Add ES6 to ES5 compiling via Babel and the sprockets es6 gem.

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

## Why was this MR needed?
So we can write ES6

## What are the relevant issue numbers?
https://gitlab.com/gitlab-org/gitlab-ce/issues/20098

## Screenshots (if relevant)
![Screen_Shot_2016-07-25_at_10.56.02_AM](/uploads/04ceeedb8235fd3a7601bc4bece313a8/Screen_Shot_2016-07-25_at_10.56.02_AM.png)

![Screen_Shot_2016-07-25_at_10.55.54_AM](/uploads/163c46a3d878924ab1717fccca468003/Screen_Shot_2016-07-25_at_10.55.54_AM.png)

## 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)
- [ ] API support added
- Tests
  - [ ] Added for this feature/bug
  - [x] 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 !5473

Signed-off-by: Rémy Coutable <remy@rymai.me>

Fix backup restore

## What does this MR do?

This MR fixes the backup restore task.

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

Whether the mode 0277 makes sense. (Group SUID + group/user read/write permissions)

## Why was this MR needed?

86359ec8 broke this, and it was not caught by any specs. Users would see:

```
Restoring repositories ...
rake aborted!
NameError: undefined local variable or method `repos_path' for #<Backup::Repository:0x00000007cea1d8>
/opt/gitlab/embedded/service/gitlab-rails/lib/backup/repository.rb:59:in `restore'
/opt/gitlab/embedded/service/gitlab-rails/lib/tasks/gitlab/backup.rake:79:in `block (4 levels) in <top (required)>'
/opt/gitlab/embedded/service/gitlab-rails/lib/tasks/gitlab/backup.rake:54:in `block (3 levels) in <top (required)>'
Tasks: TOP => gitlab:backup:repo:restore
(See full trace by running task with --trace)
```

## What are the relevant issue numbers?

#20188

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [ ] 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 !5459