HDFS-4491. Parallel testing HDFS. Contributed by Andrey Klochkov.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1520479 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4491. Add/delete files missed in prior commit.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1520482 13f79535-47bb-0310-9956-ffa450edef68
Merge remote-tracking branch: upstream/trunk