Would be useful if this repo had a licence

[evanwills]

Hi there

I've forked (and renamed) your repo for use in my organisation's team but my manager is uncomfortable about this because there's no license to so he's worried you guys might come after us for plagiarism or copyright infringement.

It would be great if this repo had a license that allowed me to do what I've done.

PS: Thanks for the awesome work. PPS: I've found some issues with the .sass-lint.yml file I'll submit a pull request later this week.