HDFS-5781. Use an array to record the mapping between FSEditLogOpCode and the corresponding byte value. Contributed by Jing Zhao.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1561788 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5825. Use FileUtils.copyFile() to implement DFSTestUtils.copyFile(). (Contributed by Haohui Mai)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1561792 13f79535-47bb-0310-9956-ffa450edef68