message: fix serving_bin download
diff: @@ -386,8 +386,6 @@ class Server(object):
  return
  if not os.path.exists(self.server_path):
  - os.system("touch {}/{}.is_download".format(self.module_path,
  - folder_name))
  print('Frist time run, downloading PaddleServing components ...')
  r = os.system('wget ' + bin_url + ' --no-check-certificate')
  @@ -403,9 +401,10 @@ class Server(object):
  tar = tarfile.open(tar_name)
  tar.extractall()
  tar.close()
  + open(download_flag, "a").close()
  except:
  - if os.path.exists(exe_path):
  - os.remove(exe_path)
  + if os.path.exists(self.server_path):
  + os.remove(self.server_path)
  raise SystemExit(
  'Decompressing failed, please check your permission of {} or disk space left.'
  .format(self.module_path))
  