YARN-1493. Changed ResourceManager and Scheduler interfacing to recognize app-attempts separately from apps. Contributed by Jian He.
svn merge --ignore-ancestry -c 1554896 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1554898 13f79535-47bb-0310-9956-ffa450edef68