HBASE-8144 Limit number of attempts to assign a region

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.95@1462215 13f79535-47bb-0310-9956-ffa450edef68
HBASE-8152 Avoid creating empty reference file when splitkey is outside the key range of a store file (clockfly)



git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.95@1462276 13f79535-47bb-0310-9956-ffa450edef68