WIP: Challenges proposal 1

My idea on how to implement Proposal 1 in #17 (closed).

Currently there are still few things to complete or to discuss, but I think we could gather these here.

• Redis storage is not implemented
• generating the session ID is not implemented
• it's not clear which methods would be async, and I haven't used it anywhere
• I'm still copying the Config, which could be avoided

Let me know what you think.