Revise Log.Warning in leave operation
Revise Log.Warning in leave operation

When do senlin-node-del command, warning log is not correct.
This patch revises this issue.
2017-01-06 11:53:35.324 WARNING ... Join operation not specialized.
2017-01-06 11:53:35.452 INFO ... end: Node successfully left cluster.
2017-01-06 11:53:37.697 INFO ...  end: Completed deleting nodes.

Change-Id: I724da330e344e48644988bcbd016cc5ce67e6058

stackforge/senlin,openstack/senlin,stackforge/senlin,openstack/senlin,openstack/senlin