Normalize network output values to 0 -> 1

[d12]

Currently, network output values are unbounded.

Before returning the output array from the final network layer, we should apply some sort of sigmoid function to the values to normalize the values.

The standard logistic sigmoid function should work just fine.

This should also be configurable though. We can allow a user to pass their own lambda in as a normalizing function incase the user want's a different output range or wants a different normalized distribution.