Make sure we have the right license

[pganssle]

I believe this should be licensed under either the PSF license or the Apache license. The data itself is public domain and comes from IANA.

[FFY00]

Looks like this should be closed as of #16.

[pganssle]

@FFY00 I think I was holding off on actually closing this until someone from the PSF weighs in as to whether they care how this is licensed — particularly if we're going to be claiming this is a "first-party package".

I am also not sure if this officially counts as something I've submitted under the umbrella of the CLA, and if we can/should be enforcing CLA compliance here (though that may be a separate issue).

I'm going to leave it open now as a reminder that this stuff is still not done (though at least there shouldn't be any legal uncertainty here, since what we have now is clearly released as Apache 2.0 and anyone can use it).