HBASE-12742

Signed-off-by: stack <stack@apache.org>
HBASE-12750 getRequestsCount() in ClusterStatus returns total number of request (Weichen Ye)
HBASE-12736

Signed-off-by: stack <stack@apache.org>
HBASE-12739 Avoid too large identifier of ZooKeeperWatcher (Liu Shaohui)