Asynchronous work

This issue is basically to start the discussion around asynchronous usage of this library, see if there are ideas/issues/restrictions around that.

I am particularly interested in working with this library from Twisted, but asyncio is now officially part of python.
There is https://github.com/crossbario/txaio which aims to be a bridge between both async frameworks.

Thoughts? Is it worth the time investment? or should I just build (and open-source) twisted-specific wrappers around authlib?

This is particularly interesting for the server side of things.