YARN-582. Changed ResourceManager to recover Application token and client tokens for app attempt so that RM can be restarted while preserving current applications. Contributed by Jian He.
svn merge --ignore-ancestry -c 1480168 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1480169 13f79535-47bb-0310-9956-ffa450edef68