Add a license

[ab-arao]

Thanks for publishing this project!

However, I didn't see a license in this repo. According to Github, this means the following:

[W]ithout a license, the default copyright laws apply, meaning that you retain all rights to your source code and no one may reproduce, distribute, or create derivative works from your work. If you're creating an open source project, we strongly encourage you to include an open source license. 

I'll submit a PR adding the MIT license shortly. Obviously you should pick whatever license you want, I just thought I'd help!