Merge -r 1475669:1475670 from trunk to branch-2. Fixes: YARN-595. Refactor fair scheduler to use common Resources. Contributed by Sandy Ryza.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1475672 13f79535-47bb-0310-9956-ffa450edef68
Merge -r 1475680:1475681 from trunk to branch-2. Fixes:  YARN-289. Fair scheduler allows reservations that won't fit on node. Contributed by Sandy Ryza.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1475682 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/branch-2' into branch-2-gd
Merge remote branch 'origin/branch-2-gd' into fb-MAPREDUCE-4884-branch-2-gd