Improve message threads (by @paroga)

plugins/messages/app/views/message_threads/index.html.haml

@@ -3,5 +3,8 @@
 - content_for :actionbar do
   = link_to t('.messages'), messages_path, class: 'btn'
   = link_to t('.new'), new_message_path, class: 'btn btn-primary'
-#message_threads
-  = render 'message_threads', message_threads: @message_threads, pagination: true
+
+= render 'groupmessage_threads', group: nil, name: t('.other'), id: 0
+
+- for group in @groups
+  = render 'groupmessage_threads', group: group, name: group.name, id: group.id