Config error when apps not installed

[nickmoreton]

The configuration, in a way expects all possible apps to be in installed apps in settings.py and that's not intended.

e.g.

wagtail.contrib.search_promotions doesn't necessarily need to be installed but when the view is run it seems to try to create the url using the name space here:

wagtail-exposapi/exposapi/views.py

Line 33 in bd47e1b

list_url = f"{url}{reverse(app['listing_name'])}"

This results in a error.