branch-trunk-win changes - unreleased

  HDFS-4145. Merge hdfs cmd line scripts from branch-1-win. (David Lao,
  Bikas Saha, Lauren Yang, Chuan Liu, Thejas M Nair and Ivan Mitic via suresh)

  HDFS-4163. HDFS distribution build fails on Windows. (Chris Nauroth via
  suresh)

  HDFS-4316. branch-trunk-win contains test code accidentally added during 
  work on fixing tests on Windows. (Chris Nauroth via suresh)

  HDFS-4297. Fix issues related to datanode concurrent reading and writing on
  Windows. (Arpit Agarwal, Chuan Liu via suresh)