YARN-1381. Same relaxLocality appears twice in exception message of AMRMClientImpl#checkLocalityRelaxationConflict() (Ted Yu via Sandy Ryza)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1537636 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9898. Set SO_KEEPALIVE on all our sockets. Contributed by Todd Lipcon.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1537638 13f79535-47bb-0310-9956-ffa450edef68
YARN-1290. Let continuous scheduling achieve more balanced task assignment (Wei Yan via Sandy Ryza)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1537735 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/branch-2' into branch-2-gd