HADOOP-6350. Document Hadoop Metrics. (Contributed by Akira Ajisaka)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1602324 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-10691. Improve the readability of 'hadoop fs -help'. Contributed by Lei Xu.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1602329 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-10678. SecurityUtil has unnecessary synchronization on collection used for only tests. Contributed by Benoy Antony.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1602473 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9629.  Set svn:ignore on new hadoop-tools/hadoop-azure directory.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1602476 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9629. Correct svn:ignore on new hadoop-tools/hadoop-azure directory.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1602477 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6330. Move mkdirs() to FSNamesystem. Contributed by Haohui Mai.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1602484 13f79535-47bb-0310-9956-ffa450edef68
HDFS-2856: small test cleanup
Merge branch 'trunk' into HDFS-2856