HBASE-9397 Snapshots with the same name are allowed to proceed concurrently (Jerry He)

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1519769 13f79535-47bb-0310-9956-ffa450edef68
HBASE-9418 REST server web UI has some dead links

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1519836 13f79535-47bb-0310-9956-ffa450edef68