YARN-1417. Modified RM to generate container-tokens not at creation time, but at allocation time so as to prevent RM
from shelling out containers with expired tokens. Contributed by Omkar Vinit Joshi and Jian He.
svn merge --ignore-ancestry -c 1568060 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1568061 13f79535-47bb-0310-9956-ffa450edef68