Change random to np.random to be consistent between py2 and py3 in Transformer

fluid/neural_machine_translation/transformer/reader.py

 import glob
 import os
-import random
 import tarfile
 
+import numpy as np
+
 
 class SortType(object):
     GLOBAL = 'global'
@@ -203,7 +204,8 @@ class DataReader(object):
         self._token_delimiter = token_delimiter
         self.load_src_trg_ids(end_mark, fpattern, start_mark, tar_fname,
                               unk_mark)
-        self._random = random.Random(x=seed)
+        self._random = np.random
+        self._random.seed(seed)
 
     def load_src_trg_ids(self, end_mark, fpattern, start_mark, tar_fname,
                          unk_mark):