YARN-854. Fixing YARN bugs that are failing applications in secure environment. Contributed by Omkar Vinit Joshi.
svn merge --ignore-ancestry -c 1494845 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1494846 13f79535-47bb-0310-9956-ffa450edef68
svn merge -c 1494854 from trunk for HDFS-4914. Use DFSClient.Conf instead of Configuration.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1494855 13f79535-47bb-0310-9956-ffa450edef68
svn merge -c 1494858 from trunk for HDFS-4908. Reduce snapshot inode memory usage.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1494859 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9451. Fault single-layer config if node group topology is enabled. (Junping Du via llu)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1494889 13f79535-47bb-0310-9956-ffa450edef68