Fix overzealous caching of static media.
Review Request #3574 — Created Nov. 27, 2012 and submitted
Fix overzealous caching of static media. When upgrading a Review Board site, the static media references would often be pointing to the wrong places. This was because Django cached the resulting media files in memcached, which is definitely not what we want. However, it will first try a "staticfiles" backend, which we can dynamically add and point to local memory instead. We do this after we've loaded the rest of the settings, ensuring we have settings.CACHES set up.
Tested locally and it seemed to work. We'll know more when we deploy next.