implement encrypted LR forward pass

[atkinssamuel]

to accomplish this, the following need to be done:

1. wrapper for SEAL forward pass functions using PyBind11
2. weight saving from Python function
3. weight loading into SEAL wrapper
4. forward pass structure

[atkinssamuel]

Can use a linear regression model to accomplish this. The linear regression with least-squares loss can be done in the encrypted domain. No need for a squared activation function if the problem is this simple.