YARN-475. Remove a unused constant in the public API - ApplicationConstants.AM_APP_ATTEMPT_ID_ENV. Contributed by Hitesh Shah.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1463033 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk-gd
Merge remote branch 'origin/trunk-gd' into fb-HADOOP-9281-trunk-gd