[WIP] badgekit api integration

This is still a WIP, and currently only allows you to create, view, and delete badges (most notably, you cannot award them yet).

This uses a modified version of the django-roa library (https://github.com/charles-vdulac/django-roa) to allow the Badge model (and soon the Award model) to use Badgekit API's REST interface as its "database" representation instead of mysql.  There are still some consequences to work out, most notably the fact that Badgekit API badges do not currently have the concept of a creator, which is fairly central to the way django-badger works.

(Note that I've just dumped the django-roa library in vendor-local rather than linking to a submodule.  It should probably be moved to a submodule eventually, but I've been making changes often enough to the module that it was much easier to not have to update a submodule every time)