YARN-707. Add user info in the YARN ClientToken. Contributed by Jason Lowe


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1520150 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5475. MRClientService does not verify ACLs properly. Contributed by Jason Lowe


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1520161 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/branch-0.23' into branch-0.23-gd
Merge remote branch 'origin/branch-0.23-gd' into fb-xxx-hadoop-auth-kerberos-realm-branch-0.23-gd