hard-coded URLs

The source code for this app contains hard references to your personal domain `androz2091.fr` in a bunch of places. This introduces a big problem: Even when hosted privately, the app makes requests to your resources. This should not happen, because that makes it impossible to truly "self"-host an instance of this app. Furthermore, this is - in my opinion - a big privacy issue, especially since there doesn't seem to be a privacy policy (depending on what the `analytics` part of the app does, this may actually be illegal).

There should be no hard references to any private URL in the source code. If some external service is inevitably required somewhere, it should be made configurable.