YARN-1253. Changes to LinuxContainerExecutor to run containers as a single dedicated user in non-secure mode. (rvs via tucu)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1529326 13f79535-47bb-0310-9956-ffa450edef68
Merge 1529369 from trunk to branch-2 for YARN-1251. TestDistributedShell#TestDSShell failed with timeout. Contributed by Xuan Gong.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1529370 13f79535-47bb-0310-9956-ffa450edef68
YARN-1167. Fixed Distributed Shell to not incorrectly show empty hostname on RM UI. Contributed by Xuan Gong.
svn merge --ignore-ancestry -c 1529376 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1529377 13f79535-47bb-0310-9956-ffa450edef68