Transfer learning tutorial should set .eval before visualizing on val

[ssnl]

The resnet18 used has BN layers which needs to be in eval mode to give good results. I'll submit a PR tomorrow.

http://pytorch.org/tutorials/beginner/transfer_learning_tutorial.html#sphx-glr-beginner-transfer-learning-tutorial-py

[chsasank]

Thanks. PR will be nice!

You need to just add model.eval() to the top of visualize_model