Making references/classification/train.py and...

Making references/classification/train.py and references/classification/utils.py  compatible with python2  (#831)

* linter fixes

* linter fixes

references/classification/train.py

+from __future__ import print_function
 import datetime
 import os
 import time

references/classification/utils.py

+from __future__ import print_function
 from collections import defaultdict, deque
 import datetime
 import time

torchvision/models/mobilenet.py

@@ -33,7 +33,6 @@ class InvertedResidual(nn.Module):
         ])
         self.conv = nn.Sequential(*layers)
 
-
     def forward(self, x):
         if self.use_res_connect:
             return x + self.conv(x)