Use new gems methods.

app/views/layouts/_init_auto_complete.html.haml

 :javascript
   GitLab.GfmAutoComplete.dataSource = "#{autocomplete_sources_project_path(@project)}"
-  GitLab.GfmAutoComplete.Emoji.assetBase = "#{Gitlab.config.gitlab.relative_url_root + '/assets/emoji'}"
+  GitLab.GfmAutoComplete.Emoji.assetBase = "#{Gitlab.config.gitlab.relative_url_root + Emoji.asset_path}"
   GitLab.GfmAutoComplete.setup();

app/views/projects/notes/_note.html.haml

@@ -23,7 +23,7 @@
         %i.icon-thumbs-up
         \+1
     - if note.downvote?
-      %span.vote.downvote.label.label-error
+      %span.vote.downvote.label.label-danger
         %i.icon-thumbs-down
         \-1

config/initializers/gemoji.rb

-# Workaround for https://github.com/github/gemoji/pull/18
-require 'gemoji'
-Gitlab::Application.config.assets.paths << Emoji.images_path

lib/gitlab/markdown.rb

@@ -152,7 +152,7 @@ module Gitlab
     #
     # Returns boolean
     def valid_emoji?(emoji)
-      Emoji.names.include? emoji
+      Emoji.find_by_name emoji
     end
     # Private: Dispatches to a dedicated processing method based on reference