'Update 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#update-namespace'

def update_namespace(self, namespace, **kwargs):

    params = {'namespace': namespace}
    params.update(kwargs)
    data = json.dumps(params)
    url = ('metadefs/namespaces/%s' % namespace)
    (resp, body) = self.put(url, body=data)
    self.expected_success(200, resp.status)
    body = json.loads(body)
    return rest_client.ResponseBody(resp, body)
