Update container metadata

        :param container: container name (Container is equivalent to
                          Bucket term in Amazon).
        :param metadata(dict): additional metadata to include in the request.
        :param **kwargs(dict): extend args for specific driver.

def update_container(self, container, metadata, **kwargs):
        """Update container metadata

        :param container: container name (Container is equivalent to
                          Bucket term in Amazon).
        :param metadata(dict): additional metadata to include in the request.
        :param **kwargs(dict): extend args for specific driver.
        """
        LOG.debug('update_object() with %s is success.', self.driver)
        return self.driver.update_container(container, metadata, **kwargs)