Fix commit comment count css

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

app/views/projects/commit/_commit_box.html.haml

 .pull-right
   %div
     - if @notes_count > 0
-      %span.btn.disabled.grouped
+      %span.btn.disabled.btn-grouped
         %i.icon-comment
         = @notes_count
     .pull-left.btn-group