HBASE-10511 Add latency percentiles on PerformanceEvaluation

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1567867 13f79535-47bb-0310-9956-ffa450edef68
HBASE-10490 Simplify RpcClient code

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1567919 13f79535-47bb-0310-9956-ffa450edef68