IssueNotesRefactor: Add GfmAutoComplete references to page.

app/views/projects/issues/_discussion.html.haml

@@ -13,6 +13,8 @@
 / #notes{style: "margin-top: 150px"}
 /   = render 'shared/notes/notes_with_form', :autocomplete => true
 
+= render "layouts/init_auto_complete"
+
 :javascript
   window.gl.issueData = #{serialize_issuable(@issue)};
   window.gl.currentUserData = #{UserSerializer.new.represent(current_user).to_json};