YARN-518. Fair Scheduler's document link could be added to the hadoop 2.x main doc page. (sandyr via tucu)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1469092 13f79535-47bb-0310-9956-ffa450edef68
YARN-476. ProcfsBasedProcessTree info message confuses users. (sandyr via tucu)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1469094 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5128. mapred-default.xml is missing a bunch of history server configs. (sandyr via tucu)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1469096 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/branch-2' into branch-2-gd
Merge remote branch 'origin/branch-2-gd' into fb-HADOOP-9078-branch-2-gd