YARN-701. Use application tokens irrespective of secure or non-secure mode. Contributed by Vinod K V.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1504604 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5265. History server admin service to refresh user and superuser group mappings. Contributed by Ashwin Shankar


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1504645 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk-gd
Merge remote branch 'origin/trunk-gd' into fb-HDFS-4312-trunk-gd