YARN-756. Move Preemption* records to yarn.api where they really belong. Contributed by Jian He.
svn merge --ignore-ancestry -c 1489290 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1489291 13f79535-47bb-0310-9956-ffa450edef68