Simplify this code and make sure AdminSite doesn't act like a singleton
Simplify this code and make sure AdminSite doesn't act like a singleton

 Create a faux-singleton for `AdminSite` and make sure it has a copy of
 all of the previously registered models.  This makes
 `armstrong.hatband.site` look just like `django.contrib.admin.site`.

texastribune/armstrong.hatband,armstrong/armstrong.hatband,texastribune/armstrong.hatband,texastribune/armstrong.hatband,armstrong/armstrong.hatband,armstrong/armstrong.hatband