'Shuts down the server
:param server_id: Id of the server to be shut down
:rtype: ``str``
:param method: Method of shutting down "SOFTWARE" or "HARDWARE"
:return:    Instance of class ``Node``
:rtype:     :class: `Node`'

def ex_shutdown_server(self, server_id, method='SOFTWARE'):

    shutdown_body = {'action': 'POWER_OFF', 'method': method}
    response = self.connection.request(action=('servers/%s/status/action' % server_id), data=shutdown_body, method='PUT')
    return self._to_node(response.object)
