HBASE-7807 Introduce HRegionFileSystem and move region fs related code

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.95@1460611 13f79535-47bb-0310-9956-ffa450edef68
HBASE-7808 Refactor Store to use HRegionFileSystem

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.95@1460612 13f79535-47bb-0310-9956-ffa450edef68
HBASE-8006 use FSUtils to get/set hbase.rootdir

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.95@1460614 13f79535-47bb-0310-9956-ffa450edef68
HBASE-7809 Refactor Split/Merge to use HRegionFileSystem

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.95@1460617 13f79535-47bb-0310-9956-ffa450edef68