YARN-363. Add webapps/proxy directory without which YARN proxy-server fails when started in stand-alone mode. Contributed by Kenji Kikushima.
svn merge --ignore-ancestry -c 1476330 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1476337 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/branch-0.23' into branch-0.23-gd
Merge remote branch 'origin/branch-0.23-gd' into fb-HADOOP-9046-branch-0.23-gd