Initial commit of badge model

This contains a slightly (though increasingly as time goes on) customized version of the django-roa module, used to allow Django models to be represeted on a remote REST API.  (In this case, badgekit api)
Ah, yeah, that is a good idea re: the defaults.  And the setup you have above is pretty much the "more elegant" solution I mentioned wanted to move to above, yeah. :)