Adding a License file

[rbharath]

Thanks for putting out this implementation! It's a really nice complement to your recent paper :)

Would you folks be willing to add a license for the code? I'd love to re-use some of the models and tools here, but can only do so with a license file.

If you're not sure what license would be good, I'd recommend MIT. It's what we use for deepchem's license

[kudkudak]

Thanks! Added the MIT license :)

[rbharath]

Great, thanks for the quick turnaround!