'Create a namespace.
For a full list of available parameters, please refer to the official
API reference:
http://developer.openstack.org/api-ref/image/v2/metadefs-index.html#create-namespace'

def create_namespace(self, **kwargs):

    data = json.dumps(kwargs)
    (resp, body) = self.post('metadefs/namespaces', data)
    self.expected_success(201, resp.status)
    body = json.loads(body)
    return rest_client.ResponseBody(resp, body)
