jQuery, Tagging, Album Art Cacheing

Replacing prototype with jQuery
Added ability to tag songs from the now playing and album pages
set expire header for album art requests

There's a ton of commits here, some of it is a little messy and i'm still learning PHP and GIT, but my fork as been my daily driver with jQuery and tagging for a few weeks now and I feel it is fairly stable.  If this pull gets merged in to ampache-doped i would like to kill off my personal fork and work with @SUTJael and @Afterster on this fork.