Add license for tooling in repository

[ann0see]

@hoffie didn't add a license to his original repository. To really have an open source project, we need a license for this repository too.

As I'm not the original author, it's up to @hoffie to decide.

The main app is licensed under the GPL while the Website is LGPL. Personally, I'd use LGPL or MIT.

What's your suggestion?

[pljones]

Given that it must be possible to verify that the signature supplied on an artifact received claiming to use the signing key from this repository is signed by that key, then I'm comfortable with LGPL, I suppose. (When I'm feeling radical about it, AGPL is quite attractive.)