HBASE-10638 Improve error message when there is no region server available for move



git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1573010 13f79535-47bb-0310-9956-ffa450edef68
HBASE-10627 A logic mistake in HRegionServer isHealthy (Shaohui)



git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1573012 13f79535-47bb-0310-9956-ffa450edef68