Subject: [Webpush] #101 Topic -> token

From: Martin Thomson <[email-masked]>
Date: Fri, 3 Jun 2016 17:01:49 +1000

Kit said:
> * Could we restrict the `Topic` grammar to just `token`? ISTM base64url already fits this definition.

https://github.com/webpush-wg/webpush-protocol/pull/101

Assuming that there are no objections, I think that this is a good
simplification.  We currently accept quoted-string, but that's an
annoying thing to handle.