ZOOKEEPER-1917 Apache Zookeeper logs cleartext admin passwords (michim via rakeshr)

git-svn-id: https://svn.apache.org/repos/asf/zookeeper/branches/branch-3.4@1631279 13f79535-47bb-0310-9956-ffa450edef68
Merge remote-tracking branch 'remotes/origin/branch-3.4' into branch-3.4