YARN-1577. Made UnmanagedAMLauncher do launchAM after the attempt reaches the LAUNCHED state. Contributed by Jian He.
svn merge --ignore-ancestry -c 1580164 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1580165 13f79535-47bb-0310-9956-ffa450edef68