HBASE-8764 Some MasterMonitorCallable should retry

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1507495 13f79535-47bb-0310-9956-ffa450edef68
HBASE-8439 [replication] Remove ReplicationZookeeper class

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1507497 13f79535-47bb-0310-9956-ffa450edef68
HBASE-9044 Merging regions throws NPE

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1507500 13f79535-47bb-0310-9956-ffa450edef68
HBASE-9048 HCM throws NullPointerException under load

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1507502 13f79535-47bb-0310-9956-ffa450edef68