Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/27655

See https://gitlab.slack.com/archives/frontend/p1489690607738864

Thanks @filipa for the shout`

 - 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

Ports changes from https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/642 back into CE

* Code in ruby now uses Array#to_sentence to construct award tooltips

* Coffeescript uses a combination of regexes for the same result

* Only the first 10 names are displayed

* Further users are indicated by "and X more."

* String "and X more" is appended to the array THEN join is called

* An oxford comma seperates the last name from "and X more"

* In coffeescript "me" is now always prepended

* Tests included