Fix getting of permissions for anonymous user

- correctly pass obj instance so that querying on model works
- temporay set user active (without saving to database) when querying
  for permissions as with Django 1.8 not active users have no
  permissions

weblate/accounts/auth.py

@@ -42,7 +42,8 @@ class WeblateUserBackend(ModelBackend):
             # Need to access private attribute, pylint: disable=W0212
             if not hasattr(user_obj, '_perm_cache'):
                 anon_user = User.objects.get(username=ANONYMOUS_USER_NAME)
-                user_obj._perm_cache = self.get_all_permissions(anon_user)
+                anon_user.is_active = True
+                user_obj._perm_cache = self.get_all_permissions(anon_user, obj)
             return user_obj._perm_cache
         return super(WeblateUserBackend, self).get_all_permissions(
             user_obj, obj