Merge branch 'mr-button-placement' into 'master'

Fixed placement of close button on merge requests

## What does this MR do?

Fixes the order in which the MR buttons appear

## Screenshots (if relevant)

![Screen_Shot_2016-06-18_at_21.41.38](/uploads/66a88ebc287b7c21160af193ee9de54c/Screen_Shot_2016-06-18_at_21.41.38.png)

![Screen_Shot_2016-06-18_at_21.41.44](/uploads/ba8f6776d79f4eb0af7877c3c71fbb54/Screen_Shot_2016-06-18_at_21.41.44.png)


See merge request !4778

app/assets/stylesheets/pages/note_form.scss

@@ -219,3 +219,16 @@
     float: left;
   }
 }
+
+.note-form-actions {
+  @media (max-width: $screen-xs-max) {
+    .btn {
+      float: none;
+      width: 100%;
+
+      &:not(:last-child) {
+        margin-bottom: 10px;
+      }
+    }
+  }
+}

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

 - content_for :note_actions do
   - if can?(current_user, :update_merge_request, @merge_request)
     - if @merge_request.open?
-      = link_to 'Close merge request', merge_request_path(@merge_request, merge_request: {state_event: :close }), method: :put, class: "btn btn-nr btn-comment btn-grouped btn-close close-mr-link js-note-target-close", title: "Close merge request", data: {original_text: "Close merge request", alternative_text: "Comment & close merge request"}
+      = link_to 'Close merge request', merge_request_path(@merge_request, merge_request: {state_event: :close }), method: :put, class: "btn btn-nr btn-comment btn-close close-mr-link js-note-target-close", title: "Close merge request", data: {original_text: "Close merge request", alternative_text: "Comment & close merge request"}
     - if @merge_request.closed?
-      = link_to 'Reopen merge request', merge_request_path(@merge_request, merge_request: {state_event: :reopen }), method: :put, class: "btn btn-nr btn-comment btn-grouped btn-reopen reopen-mr-link js-note-target-reopen", title: "Reopen merge request", data: {original_text: "Reopen merge request", alternative_text: "Comment & reopen merge request"}
+      = link_to 'Reopen merge request', merge_request_path(@merge_request, merge_request: {state_event: :reopen }), method: :put, class: "btn btn-nr btn-comment btn-reopen reopen-mr-link js-note-target-reopen", title: "Reopen merge request", data: {original_text: "Reopen merge request", alternative_text: "Comment & reopen merge request"}
 
 #notes= render "projects/notes/notes_with_form"