Issue #1009 Custom User field not getting read from compat.py during ApiAuthentication

        If using a custom User model with create_api_key signal, it is possible that 
        this module was not loaded properly (because the custom user model was not
        setup by then, see compat.py :ImproperlyConfigured exception for more details).
        In that case, reloading the module will get the correct custom User module
        (otherwise sometimes the User model is None)