Improve message threads (by @paroga)

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

@@ -0,0 +1,11 @@
+- message_threads = Message.pub.threads.where(group: group).order(created_at: :desc).limit(5)
+- unless message_threads.empty?
+  %section
+    %h3
+      = name
+      %small
+        = link_to message_thread_path(id) do
+          = t '.show_message_threads'
+          %i.icon.icon-chevron-right
+    = render 'message_threads', message_threads: message_threads, pagination: false
+    = link_to_top