HBASE-8451 MetricsMBeanBase has concurrency issues in init (Liang Xie)



git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1476713 13f79535-47bb-0310-9956-ffa450edef68
HBASE-8436 SeekBefore returns wrong result with PREFIX_TREE Encoding

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1476730 13f79535-47bb-0310-9956-ffa450edef68