Speed up bcrypt / basic auth

Bcrypt / Basic auth adds a certain overhead to the http connections.

We should somehow cache successful valid logins to speed them up.

See https://github.com/caddyserver/caddy/issues/3462 and https://github.com/caddyserver/caddy/commit/9a7756c6e4b4ddb945bede3ddb2dfbf241208915