Fix: Tags and Sources in Sidebar not clickable after adding/saving source

After a Source is saved all Sidebar "Links" are deleted and reimplemented (to refresh them?). unfortunatly the `nav-tags > li` click-event is only set on startup.
Solution:
Changed the jQuery event to `.on()` which adds events if elements are created on runtime.
Performance is not worse than individual adding every `li` http://www.brentsowers.com/2012/03/jquery-on-performance.html