HBASE-8754 Log the client IP/port of the balancer invoker

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1516479 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk-gd
Merge remote branch 'origin/trunk-gd' into fb-YAHOO-325-trunk-gd