TF2 compatible and pypi publish

[chnzhangrui]

It works with TF2 now without explicit Keras.
I also made a channel for it https://pypi.org/project/nnlo/0.0.4/.
MNIST example now runs with

pip install nnlo
GetData MNIST
jsrun -n 12 -g 1 TrainingDriver --model mnist --loss categorical_crossentropy --epochs 1
jsrun -n 12 -g 1 TrainingDriver --model mnist_torch --loss categorical_crossentropy --epochs 1