Get the client's secrets using the client_id

        :param client_id: the client ID, e.g. a service ID
        :returns: list OAuthSecret instances

def client_secrets(cls, client_id):
        """
        Get the client's secrets using the client_id

        :param client_id: the client ID, e.g. a service ID
        :returns: list OAuthSecret instances
        """
        secrets = yield cls.view.get(key=client_id, include_docs=True)
        raise Return([cls(**secret['doc']) for secret in secrets['rows']])