Revisit urls schemes

One-sentence description

Revisit urls schemes

Why?

It's currently a bit messy and not consistent.

Current implementation

We have one central urls.py for our application in thaliawebsite which decides the namespacing of all the modules.

Suggested implementation

The central urls.py only includes the urls.py files of all the packages. These packages are then allowed to fill in their url schemes how they see fit. This allows us to re-use the same namespace in multiple modules and follow the way our menu is structured to decide the full url of a page.

All urls used in the django admin and implemented via the central urls.py (like push notifications and newsletters) should be implemented using the ModelAdmin's get_urls method like it was done in registrations and payments.