Adding a licence

[dblenkus]

First I would like to thank you for this great piece of code! It is exactly what I was looking for.

Would you mind adding a License file to the repository? So we can legally use (and modify) the code - under whichever license suits you the most.

Here is a short article that you can use as a help for setting it up: https://help.github.com/articles/adding-a-license-to-a-repository/

Thanks,
Domen