YARN-600. Hook up cgroups CPU settings to the number of virtual cores allocated. (sandyr via tucu)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1-beta@1492369 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5259. Merging change r1492367 from branch-2 to branch-2.1-beta.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1-beta@1492374 13f79535-47bb-0310-9956-ffa450edef68
YARN-648. FS: Add documentation for pluggable policy. (kkambatl via tucu)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1-beta@1492390 13f79535-47bb-0310-9956-ffa450edef68
YARN-700. Merging change r1492386 from branch-2 to branch-2.1-beta.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1-beta@1492396 13f79535-47bb-0310-9956-ffa450edef68