merge YARN-615 from trunk. Rename ContainerLaunchContext.containerTokens to tokens. Contributed by Vinod Kumar Vavilapalli.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1482200 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5222. Bring back some methods and constants in Jobclient for binary compatibility with mapred in 1.x. Contributed by Karthik Kambatla.
svn merge --ignore-ancestry -c 1482208 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1482209 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9459. ActiveStandbyElector can join election even before Service HEALTHY, and results in null data at ActiveBreadCrumb. Contributed by Vinay and Todd Lipcon.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1482226 13f79535-47bb-0310-9956-ffa450edef68