…rite or read.

When doing DFSIO test as a distributed i/o benchmark tool. Then especially writes plenty of files to disk or read from, both can cause performance issue and imprecise value in a way. The question is that existing practices needs to delete files when before running a job and that will cause extra time consumption and furthermore cause performance issue, statistical time error and imprecise throughput while the files are lots of. So we need to replace or improve this hack to prevent this from happening in the future.

…efault permissions. Contributed by Wellington Chevreuil.

…ao Chen.

…f. Contributed by Shen Yinjie.

…encies. (ozawa)

…er#testCheckThatNameNodeResourceMonitorIsRunning. Contributed by Rakesh R

…cs and per FS storage stats. Contributed by Mingliang Liu.

…. Contributed by niccolo becchi.

This closes #108