HBASE-7513 HDFSBlocksDistribution shouldn't send NPEs when something goes wrong

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1430560 13f79535-47bb-0310-9956-ffa450edef68
HBASE-7518 Move AuthResult out of AccessController

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1430631 13f79535-47bb-0310-9956-ffa450edef68