Switched to johnny-cache from git

There is a bug in Johnny Cache / Django 1.5.1 which has been fixed
in master, but there has been no PyPi release. For now, we'll have
to install from Github. I've included a specific commit, to try
and avoid issues with running from the bleeding edge.
Added anit-clickjacking middleware
Merge remote-tracking branch 'origin/master' into development