Ensure empty recipients are rejected in BuildsEmailService

Fixes #14883.

See merge request !3543

Optimise .gitlab-ci.yml

Not sure who should I assign.



See merge request !3542

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

Added bottom margin to CLI instructions

The CLI instructions block in the empty project page is missing a margin-bottom style property. I added it, you can review the only line I edited to add this.

This only fixes a UX bug (to me), related to the "Remove project" button that is not correctly padded. Now I believe that part look better :)

I attach screenshots.

### before
![Selezione_009](/uploads/f46b2a26c192a0b1994ff2f037f50e6c/Selezione_009.png)

### after
![Selezione_008](/uploads/33a9451bbe8bfd9abd300f9c6eb4005f/Selezione_008.png)

See merge request !3505

API: Ability to retrieve a single tag

* Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/14330

/cc @dblessing 

See merge request !3567

Add CI styling to all CI updates

Fixes #14942 

Correct styling for last commit:
![Screen_Shot_2016-04-05_at_2.17.54_PM](/uploads/8cbda0023eaf7a26b776f3da58050e1a/Screen_Shot_2016-04-05_at_2.17.54_PM.png)

See merge request !3554

Fix Error 500 after renaming a project path

Renaming the path of a project would result in an Error 500 due to `@repository` being memoized with the old path. An Error 500 would result:

```
Started GET "/testing2/test1" for 127.0.0.1 at 2016-04-04 12:42:30 +0000
Processing by ProjectsController#show as HTML
  Parameters: {"namespace_id"=>"testing2", "id"=>"test1"}
Completed 200 OK in 637ms (Views: 194.2ms | ActiveRecord: 111.8ms)
Started GET "/testing2/test1/edit" for 127.0.0.1 at 2016-04-04 12:42:33 +0000
Processing by ProjectsController#edit as HTML
  Parameters: {"namespace_id"=>"testing2", "id"=>"test1"}
Completed 200 OK in 594ms (Views: 183.8ms | ActiveRecord: 87.4ms)
Started PATCH "/testing2/test1" for 127.0.0.1 at 2016-04-04 12:42:41 +0000
Processing by ProjectsController#update as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"[FILTERED]", "project"=>{"nam
e"=>"test123", "path"=>"test123"}, "namespace_id"=>"testing2", "id"=>"test1"}
Completed 500 Internal Server Error in 1852ms (ActiveRecord: 124.0ms)

ActionView::Template::Error (no repository for such path):
    2:   %legend
    3:     Builds:
    4:
    5:   - unless @repository.gitlab_ci_yml
    6:     .form-group
    7:       .col-sm-offset-2.col-sm-10
    8:         %p Builds need to be configured before you can begin using Contin
uous Integration.
  app/models/repository.rb:59:in `block in empty?'
  lib/repository_cache.rb:19:in `fetch'
  app/models/repository.rb:59:in `empty?'
  app/models/repository.rb:471:in `gitlab_ci_yml'
  app/views/projects/_builds_settings.html.haml:5:in `_app_views_projects__build
s_settings_html_haml__782034335636359229_73397600'
  app/views/projects/edit.html.haml:87:in `block in _app_views_projects_edit_htm
l_haml___2388082585934859365_47390860'
  app/views/projects/edit.html.haml:8:in `_app_views_projects_edit_html_haml___2
388082585934859365_47390860'
  app/controllers/projects_controller.rb:54:in `block (2 levels) in update'
  app/controllers/projects_controller.rb:43:in `update'
  lib/gitlab/middleware/go.rb:16:in `call'
```

Closes #14885

See merge request !3528

Premailer shouldn't remove script tags from our emails

Closes #14943.

See merge request !3552

[ci skip]

Closes #14943.

Fix data check in update issue response



See merge request !3548

Dropdown arrow support

When the dropdown is open, you can scroll through the list of items with the up & down arrow keys. When an item is focused, the enter triggers the click event for that row.

Closes #14455

See merge request !3385

Notes form design update

Part of #3401

See merge request !3442

Closes #14885

[ci skip]

Attribution where it is due.

Inspired by https://news.ycombinator.com/item?id=11431969

See merge request !3546

Upgrade bundler-audit from 0.4.0 to 0.5.0

Bundler Audit can now run the `check` command with an `—update` flag to update the Ruby CVE repository before checking. This removes the need for two separate commands in GitLab CI ([source](https://github.com/rubysec/bundler-audit#synopsis)).

See the Changelog for more information: https://github.com/rubysec/bundler-audit/blob/master/ChangeLog.md#050--2015-02-28

See merge request !3433

Check permissions when importing project members

Closes #14899

See merge request !3535

[ci skip]
Signed-off-by: Rémy Coutable <remy@rymai.me>

[ci skip]
Signed-off-by: Rémy Coutable <remy@rymai.me>

Fix LDAP link and codeblock indentation



See merge request !3538

[ci skip]

Update language after doing all other operations

See merge request !3533

Added CHANGELOG for build notifications

[ci skip]

See merge request !3537

[ci skip]

Add comments to the SCSS Lint config file [ci skip]

This MR also adds some previously missing linters.

See merge request !3500

When importing members, and user does not have permissions to read
members in a source project, do not leak information about source
project existence. Notifiy user that project has not been found instead.

Add missing changelog item about improving navigation sidebar
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

For !3494 and #14838 

See merge request !3527

Closes #14899

Fix Importing repos from GHE doesn't work

See merge request !3529