YARN-1210. Changed RM to start new app-attempts on RM restart only after ensuring that previous AM exited or after expiry time. Contributed by Omkar Vinit Joshi.
svn merge --ignore-ancestry -c 1543310 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1543311 13f79535-47bb-0310-9956-ffa450edef68