Returns a restclients.Key object for the given resource.  If the
        resource isn't found, or if there is an error communicating with the
        KWS, a DataFailureException will be thrown.

def get_current_key(self, resource_name):
        """
        Returns a restclients.Key object for the given resource.  If the
        resource isn't found, or if there is an error communicating with the
        KWS, a DataFailureException will be thrown.
        """
        url = ENCRYPTION_CURRENT_KEY_URL.format(resource_name)
        return self._key_from_json(self._get_resource(url))