Fix, maybe cannot deleteChildren completely when multi-client delete concurrently

[he7g]

No description provided.

[Randgalt]

Please review https://cwiki.apache.org/confluence/display/CURATOR/Submitting+Pull+Requests

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[Randgalt]

Also, I don't know what the need for this is. ZKPaths is an internal utility and the Curator code that uses it already ignores the exception.

[he7g]

use curatorFramework.delete().deletingChildrenIfNeeded().forPath(path), this sync api doesn't ignore the NoNodeException, causes the rest of children nodes will not be deleted perhaps.

zookeeper.getChildren(path, null) maybe throw NoNodeException, if the path doesn't exist.

[he7g]

see #235, please