YARN-1342. Recover container tokens upon nodemanager restart. Contributed by Jason Lowe.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1612995 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-10882. Move DirectBufferPool into common util. Contributed by Todd Lipcon.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1613006 13f79535-47bb-0310-9956-ffa450edef68