OOZIE-1606 Update Curator to 2.3.0 and fix some misc minor ZK related things (rkanter)

git-svn-id: https://svn.apache.org/repos/asf/oozie/trunk@1541733 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk
Merge remote branch 'origin/trunk' into trunk-gd