Fix problems with award-emoji-only comment

This fixes a conflict between note with only a single emoji in content
and award-emojis mechanisms.

Closes #3734 

cc @vsizov

See merge request !1936

Fix Error 500 when creating global milestones with Unicode characters

Two issues:

1. The constraints in the resources were incorrect. Here's what it was before:

```
group_milestone  GET /groups/:group_id/milestones/:id(.:format)  groups/milestones#show {:id=>/[a-zA-Z.0-9_\-]+(?<!\.atom)/, :group_id=>/[a-zA-Z.0-9_\-]+(?<!\.atom)/}
```

In this case, id is actually the title of the milestone, which can be anything at the moment.

After:
```
group_milestone  GET /groups/:group_id/milestones/:id(.:format)  groups/milestones#show {:id=>/[^\/]+/, :group_id=>/[a-zA-Z.0-9_\-]+(?<!\.atom)/}
```

2. `parameterize` would strip all Unicode characters, leaving a blank string. Rails would report something like:

```
ActionView::Template::Error (No route matches {:action=>"show", :controller=>"groups/milestones", :group_id=>#<Group id: 48, name: "ops-dev", path: "ops-dev", owner_id: nil, created_at: "2015-11-15 08:55:30", updated_at: "2015-12-02 06:23:26", type: "Group", description: "", avatar: "sha1.c71e73d51af1865c1bbbf6208e10044d46c9bb93.png", public: false>, :id=>"", :title=>"肯定不是中文的问题"} missing required keys: [:id]):
```

This change uses the babosa library to create a better slug, which surprisingly
isn't actually used by the global milestone controllers. Instead, they use the
title passed as a query string for some reason.

Closes https://github.com/gitlabhq/gitlabhq/issues/9881

See merge request !1983

Style warning about mentioning many people in a comment

Fixes #2885 

* Create issue:

    Before:

    ![Screenshot_2015-12-03_15.23.44](/uploads/6da9b326e47dc5e8c127a581af99403c/Screenshot_2015-12-03_15.23.44.png)

    After:

    ![Screenshot_2015-12-03_15.21.29](/uploads/bbe328d30a32d642c280bf2ad6d2832c/Screenshot_2015-12-03_15.21.29.png)  
      

* New merge request:

    Before:

    ![Screenshot_2015-12-03_15.24.06](/uploads/79d6f8f52ba2753aaecf6b6bbd04f0d0/Screenshot_2015-12-03_15.24.06.png)

    After:

    ![Screenshot_2015-12-03_15.21.48](/uploads/f01ea8e7d058a9f8b803ca1ce4f533ad/Screenshot_2015-12-03_15.21.48.png)
     

* New comment in a merge request:

    Before:

    ![Screenshot_2015-12-03_15.11.23](/uploads/5d958375812d21d41e00694186c7ef7a/Screenshot_2015-12-03_15.11.23.png)

    After:

    ![Screenshot_2015-12-03_15.09.08](/uploads/3d6bde6aad46c7d9e53b70a47eecf7c0/Screenshot_2015-12-03_15.09.08.png)
     

* New diff comment:

    Before:

    ![Screenshot_2015-12-03_15.25.50](/uploads/08ac9c261c1aa9693706da714c121e15/Screenshot_2015-12-03_15.25.50.png)

    After:

    ![Screenshot_2015-12-03_15.46.20](/uploads/07a8b8708ad825eb8cda7e5e40116b81/Screenshot_2015-12-03_15.46.20.png)

See merge request !1971

Check GitLab Workhorse status in init.d script when reporting all components are up and running

Closes https://github.com/gitlabhq/gitlabhq/issues/9869

See merge request !1969

Fixed duplicated issue note email notifications.

Fixes #2560 



See issue for the details.

Without `uniq` modified tests were failing with:
```
     Failure/Error: notification.new_note(note)
       (Notify (class)).note_issue_email(21, 1)
           expected: 1 time with arguments: (21, 1)
           received: 2 times with arguments: (21, 1)
     # /home/bak1an/.rvm/gems/ruby-2.1.6@gitlab/gems/sidekiq-3.3.0/lib/sidekiq/extensions/action_mailer.rb:17:in `public_send'
     # /home/bak1an/.rvm/gems/ruby-2.1.6@gitlab/gems/sidekiq-3.3.0/lib/sidekiq/extensions/action_mailer.rb:17:in `perform'
     # /home/bak1an/.rvm/gems/ruby-2.1.6@gitlab/gems/sidekiq-3.3.0/lib/sidekiq/testing.rb:74:in `block in raw_push'
     # /home/bak1an/.rvm/gems/ruby-2.1.6@gitlab/gems/sidekiq-3.3.0/lib/sidekiq/testing.rb:69:in `each'
     # /home/bak1an/.rvm/gems/ruby-2.1.6@gitlab/gems/sidekiq-3.3.0/lib/sidekiq/testing.rb:69:in `raw_push'
     # /home/bak1an/.rvm/gems/ruby-2.1.6@gitlab/gems/sidekiq-3.3.0/lib/sidekiq/client.rb:68:in `push'
     # /home/bak1an/.rvm/gems/ruby-2.1.6@gitlab/gems/sidekiq-3.3.0/lib/sidekiq/worker.rb:85:in `client_push'
     # /home/bak1an/.rvm/gems/ruby-2.1.6@gitlab/gems/sidekiq-3.3.0/lib/sidekiq/extensions/generic_proxy.rb:19:in `method_missing'
     # ./app/services/notification_service.rb:144:in `block in new_note'
     # ./app/services/notification_service.rb:143:in `each'
     # ./app/services/notification_service.rb:143:in `new_note'
     # ./spec/services/notification_service_spec.rb:63:in `block (5 levels) in <top (required)>'
```

I have also added `once` to all `should_email` checks within `notification_service_spec.rb` since it's probably the correct behavior to notify users only once on the same event. Nothing else failed out of the box but we can keep these assertions for future.

See merge request !1925

Fixes #2560

[ci skip]

Clarify Project Limit Reached

Two issues:

1. The constraints in the resources were incorrect. Here's what it was before:
```
group_milestone  GET /groups/:group_id/milestones/:id(.:format)  groups/milestones#show {:id=>/[a-zA-Z.0-9_\-]+(?<!\.atom)/, :group_id=>/[a-zA-Z.0-9_\-]+(?<!\.atom)/}
```

In this case, id is actually the title of the milestone, which can be anything at the moment.

After:

```
group_milestone  GET /groups/:group_id/milestones/:id(.:format)  groups/milestones#show {:id=>/[^\/]+/, :group_id=>/[a-zA-Z.0-9_\-]+(?<!\.atom)/}
```

2. `parameterize` would strip all Unicode characters, leaving a blank string. Rails would report something like:

ActionView::Template::Error (No route matches {:action=>"show", :controller=>"groups/milestones", :group_id=>#<Group id: 48, name: "ops-dev", path: "ops-dev", owner_id: nil, created_at: "2015-11-15 08:55:30", updated_at: "2015-12-02 06:23:26", type: "Group", description: "", avatar: "sha1.c71e73d51af1865c1bbbf6208e10044d46c9bb93.png", public: false>, :id=>"", :title=>"肯定不是中文的问题"} missing required keys: [:id]):

This change uses the babosa library to create a better slug, which surprisingly
isn't actually used by the global milestone controllers. Instead, they use the
title passed as a query string for some reason.

Closes https://github.com/gitlabhq/gitlabhq/issues/9881

Fix constraints

Recognize issue/MR/snippet/commit links as references.

Fixes #3744 and #3745

See merge request !1933

[ci skip]

Ensure "Remove Source Branch" button is not shown when branch is being deleted.

Given the merging of the Merge Request happens in the background, sometimes when the client JS code reloads the page the source branch is not still gone.

This fix appends a new query string parameter that is checked in the view before rendering the `Remove Source Branch` button.

Closes #3583

See merge request !1897

Fix application settings cache not expiring after changes

cache_key is an instance method that relies on updated_at. When changes
were made, the time-dependent key was being used instead of X.application_setting.last.

Closes #3609 


See merge request !1972

Make current user the first user in assignee dropdown in issues detail page

Closes #3679

See merge request !1913

Closes #3679

Closes https://github.com/gitlabhq/gitlabhq/issues/9869

cache_key is an instance method that relies on updated_at. When changes
were made, the time-dependent key was being used instead of X.application_setting.last.

Closes #3609

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

Add API endpoint to fetch merge request commits list

Fixes #3748 

See merge request !1984

Fix mailers queue

The `mailer` queue can be removed.

See merge request !1975

* add note to Events API
* add author section to Events API
* add noteable_id and noteable_type to Notes API
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

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

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

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

UI: Sidebar & header tweaks and fixes

Depends on !1953 

See the commits for more details, the messages mostly speak for themselves.

![Logo](https://gitlab.com/gitlab-org/gitlab-ce/uploads/ba088150165bb0a0aea1e894f3443f43/logo_tooltip.png)

![Sidebar](https://gitlab.com/gitlab-org/gitlab-ce/uploads/c1e8c09ac3bf489cdb9531eebea18c90/sidebar_tooltips.png)

Fixes #2928, #2071, https://dev.gitlab.org/gitlab/gitlabhq/issues/2575, and https://dev.gitlab.org/gitlab/gitlabhq/issues/2573

See merge request !1958