HBASE-8165 Move to Hadoop 2.1.0-beta from 2.0.x-alpha (WAS: Update our protobuf to 2.5 from 2.4.1)

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1516084 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk-gd
Merge remote branch 'origin/trunk-gd' into fb-HBASE-8559-trunk-gd