YARN-1749. Updated application-history related configs to reflect the latest reality and to be consistently named. Contributed by Zhijie Shen.
svn merge --ignore-ancestry -c 1570948 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1570949 13f79535-47bb-0310-9956-ffa450edef68
YARN-1742. Fixed javadoc of configuration parameter DEFAULT_NM_MIN_HEALTHY_DISKS_FRACTION. Contributed by Akira Ajisaka.
svn merge --ignore-ancestry -c 1570956 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1570957 13f79535-47bb-0310-9956-ffa450edef68