License update

[henrygab]

As a contributor to this repository, and in support of transition to MIT, Apache, and EUPL licenses:

I hereby dedicate to the public all my rights to the code changes found in pull request #57.

Please consider dual-licensing under EUPL and one of MIT or Apache licenses....

[jacob-willden]

Thanks for granting permission, @henrygab! I'm in the process of contacting all other contributors to get their permission to license their contributions under a free license. I'll post when I hear back from everyone.