Merge branch 'pberndt:master' into 'master'

Fix #3758: Serious performance issues due to timeago()
being called n*(n+1)/2 times instead of n

See bug #3758 for a description. This merge request alters 
`time_ago_with_tooltip` to invoke the `timeago()` javascript on the
current timestamp only, instead of each one defined on the page so far.

See merge request !1977

app/helpers/application_helper.rb

@@ -209,7 +209,7 @@ module ApplicationHelper
       title: time.in_time_zone.stamp('Aug 21, 2011 9:23pm'),
       data: { toggle: 'tooltip', placement: placement, container: 'body' }
-    element += javascript_tag "$('.js-timeago').timeago()" unless skip_js
+    element += javascript_tag "$('.js-timeago').last().timeago()" unless skip_js
     element
   end