HDFS-5366. recaching improvements (cmccabe)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1541647 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5440. Extract the logic of handling delegation tokens in HftpFileSystem to the TokenAspect class. Contributed by Haohui Mai.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1541665 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9594 commons-math

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1541672 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5431 Missing pom dependency in MR-client

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Merge remote branch 'origin/trunk' into trunk-gd
Merge remote branch 'origin/trunk-gd' into fb-HDFS-4312-trunk-gd