Helper method for gettings the groups that
        are present in the local db but not on stormpath
        and the other way around.

def _get_group_difference(self, sp_groups):
        """Helper method for gettings the groups that
        are present in the local db but not on stormpath
        and the other way around."""
        db_groups = set(Group.objects.all().values_list('name', flat=True))
        missing_from_db = set(sp_groups).difference(db_groups)
        missing_from_sp = db_groups.difference(sp_groups)

        return (missing_from_db, missing_from_sp)