YARN-981. Fixed YARN webapp so that /logs servlet works like before. Addendum patch to fix bugs in the first patch. Contributed by Jian He.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1519208 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk-gd
Merge remote branch 'origin/trunk-gd' into fb-HDFS-4310-trunk-gd