HBASE-8081. Backport HBASE-7213 (separate hlog for meta tables) (Devaraj Das).

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.94@1461314 13f79535-47bb-0310-9956-ffa450edef68
HBASE-8199 Eliminate exception for ExportSnapshot against the null table snapshot (Julian Zhou)

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.94@1461346 13f79535-47bb-0310-9956-ffa450edef68