[WIP] Code for Chapters 4 and 5

[rbharath]

Additions:

• Adds code for fully connected simple models
• Adds minibatched, fully connected tox21 example
• Adds function version of tox21 fcnet for hyperparameter search.

TODOs: Need to add

• hyperparam grid search example
• hyperparam random search example
• full blown hyperparam search example