Merge -c 1548336 from trunk to branch-2 to fix YARN-1438. Ensure container diagnostics includes exception from container launch. Contributed by Steve Loughran.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1548337 13f79535-47bb-0310-9956-ffa450edef68