YARN-1613. Fixed the typo with the configuration name YARN_HISTORY_SERVICE_ENABLED. Contributed by Akira Ajisaka.
svn merge --ignore-ancestry -c 1561461 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1562226 13f79535-47bb-0310-9956-ffa450edef68