YARN-975. Added a file-system implementation for HistoryStorage. Contributed by Zhijie Shen.
svn merge --ignore-ancestry -c 1536942 ../../branches/YARN-321-old/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/YARN-321@1556727 13f79535-47bb-0310-9956-ffa450edef68