HBASE-10439 Document how to configure REST server impersonation

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1565818 13f79535-47bb-0310-9956-ffa450edef68
HBASE-10482 ReplicationSyncUp doesn't clean up its ZK, needed for tests

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1565837 13f79535-47bb-0310-9956-ffa450edef68