HDFS-4393. Merge 1434844 from trunk.

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svn merge -c 1434868 FIXES: HADOOP-8849. FileUtil#fullyDelete should grant the target directories +rwx permissions (Ivan A. Veselovsky via bobby)


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1434870 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4415. HostnameFilter should handle hostname resolution failures and continue processing. Contributed by Robert Kanter.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1434952 13f79535-47bb-0310-9956-ffa450edef68
YARN-331. Fill in missing fair scheduler documentation. (sandyr via tucu)

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MAPREDUCE-4923. Add toString method to TaggedInputSplit. (sandyr via tucu)

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YARN-302. Fair scheduler assignmultiple should default to false. (sandyr via tucu)

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HDFS-4359. Slow RPC responses from NN can prevent metrics collection on DNs. Contributed by liang xie.


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merge MAPREDUCE-4948 from trunk. Fix a failing unit test - TestYARNRunner.testHistoryServerToken. Contributed by Junping Du


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svn merge -c 1435386 FIXES: MAPREDUCE-4458. Warn if java.library.path is used for AM or Task (Robert Parker via jeagles)

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