Package, tar, and copy usr_dir to GCS train_dir.

def tar_and_copy_usr_dir(usr_dir, train_dir):
  """Package, tar, and copy usr_dir to GCS train_dir."""
  tf.logging.info("Tarring and pushing t2t_usr_dir.")
  usr_dir = os.path.abspath(os.path.expanduser(usr_dir))
  # Copy usr dir to a temp location
  top_dir = os.path.join(tempfile.gettempdir(), "t2t_usr_container")
  tmp_usr_dir = os.path.join(top_dir, usr_dir_lib.INTERNAL_USR_DIR_PACKAGE)
  shutil.rmtree(top_dir, ignore_errors=True)
  shutil.copytree(usr_dir, tmp_usr_dir)
  # Insert setup.py if one does not exist
  top_setup_fname = os.path.join(top_dir, "setup.py")
  setup_file_str = get_setup_file(
      name="DummyUsrDirPackage",
      packages=get_requirements(usr_dir)
  )
  with tf.gfile.Open(top_setup_fname, "w") as f:
    f.write(setup_file_str)
  usr_tar = _tar_and_copy(top_dir, train_dir)
  return usr_tar