HBASE-7403 Online Merge(Chunhui shen)

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.95@1460310 13f79535-47bb-0310-9956-ffa450edef68
HBASE-8189 Shell commands of online region merge(Chunhui shen)

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.95@1460312 13f79535-47bb-0310-9956-ffa450edef68