`zip` should be `izip` in bayesian_neural_network.ipynb

[alxempirical]

Maybe these are python 2 vs python 3 differences. I am running 2.

This code blows up because it's trying to generate an infinite list.

minibatches = zip(
    Xminibatch, 
    Yminibatch,
)

[twiecki]

Should be fixed with a567c9e.