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

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

 + rename controler method to #index from #metrics
 + remove assertion from nullMetric

This reverts commit b0498c17

 - gl_emoji for falling back to image/css-sprite when the browser
   doesn't support an emoji
 - Markdown rendering (Banzai filter)
 - Autocomplete
 - Award emoji menu
    - Perceived perf
    - Immediate response because we now build client-side
 - Update `digests.json` generation in gemojione rake task to be more
   useful and  include `unicodeVersion`

MR: !9437

See issues

 - #26371
 - #27250
 - #22474

`API::API` is autoloaded and shouldn't be required in non-autoloaded
code. Otherwise, we get the following dreaded error:

  A copy of API::Helpers has been removed from the module tree but is
  still active!
Signed-off-by: Rémy Coutable <remy@rymai.me>

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

This commit includes a couple of thing:
- A chatops controller
- Mattermost::CommandService
- Mattermost::Commands::(IssueService|MergeRequestService)

The controller is the point where mattermost, and later slack will have
to fire their payload to. This in turn will execute the CommandService.

Thats where the authentication and authorization should happen. So far
this is not yet implemented. This should happen in later commits.

Per subcommand, in case of `/gitlab issue show 123` issue whould be the
subcommand, there is a service to parse the data, and fetch the
resource. The resource is passed back to the CommandService which
structures the data.

* split on multiple files
* improve routing order
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

- Tab between register and sign in forms
- Add individual input validation error messages
- Validate username
- Update many styles for all login-box forms

We need this to prevent routing error when user access URL like /123
when there is no resource located under such name
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

The main purpose of this controller was redirect to group or user page
when URL like https://gitlab.com/gitlab-org was used. Now this
functionality is handled by contrainers and take user to correct
controller right from the start
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Used variables in haml for replicated checks
Fixed broken conflict

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>

- Move things common to `Issue` and `MergeRequest` into `Issuable`
- Move more database-specific functions into `Gitlab::Database`
- Indentation changes and other minor refactorings.

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

1. Code is messy and untested, but it is a start.