Create a rebased CONNECTORS-867 branch

git-svn-id: https://svn.apache.org/repos/asf/manifoldcf/branches/CONNECTORS-867@1560678 13f79535-47bb-0310-9956-ffa450edef68
Add calling infrastructure for ZooKeeper blocking locks

git-svn-id: https://svn.apache.org/repos/asf/manifoldcf/branches/CONNECTORS-867@1560685 13f79535-47bb-0310-9956-ffa450edef68
Debug zookeeper no-busy-wait locks

git-svn-id: https://svn.apache.org/repos/asf/manifoldcf/branches/CONNECTORS-867@1560796 13f79535-47bb-0310-9956-ffa450edef68
Fix for CONNECTORS-867.

git-svn-id: https://svn.apache.org/repos/asf/manifoldcf/trunk@1560841 13f79535-47bb-0310-9956-ffa450edef68