General deep learning solver of agent optimization problem

[sbenthall]

A nice-to-have feature based on the conversation today ...

A general solver to models defined using HARK.frame that uses a (deep) neural network for its solution/policy functions.

The idea is to use Tensorflow to simulation the model forward and use the resulting utility as a loss function, which is then reduced through deep learning training techniques.

Some work by Pablo for inspiration:

https://notes.quantecon.org/submission/5ddb3c926bad3800109084bf