Stop a node ("pulling the plug").

    CLI Example:

    .. code-block:: bash

        salt-cloud -a stop mymachine

def stop(name, vmid=None, call=None):
    '''
    Stop a node ("pulling the plug").

    CLI Example:

    .. code-block:: bash

        salt-cloud -a stop mymachine
    '''
    if call != 'action':
        raise SaltCloudSystemExit(
            'The stop action must be called with -a or --action.'
        )

    if not set_vm_status('stop', name, vmid=vmid):
        log.error('Unable to bring VM %s (%s) down..', name, vmid)
        raise SaltCloudExecutionFailure

    # xxx: TBD: Check here whether the status was actually changed to 'stopped'

    return {'Stopped': '{0} was stopped.'.format(name)}