After successful consent we redirected users only when their original
URL started with http (and not: https). We redirect to https only now.

This enviroment var ("localhost" by default) tells which domain we want
to cover. The given domain will be set in the consent cookie and only be
sent to the given server.

Using docker-compose eases things remarkably.

No need to use `/app/app` when `/app` is not used otherwise.

This one is based on Python instead of Rust and easier to be changed,
due to usage of docker and possible rebuilds of the web app.