[FEAT] Move a lot of content/settings to Constance

They can now be changed in the Django admin interface

breccia_mapper/urls.py

@@ -14,7 +14,9 @@ Including another URLconf
     2. Add a URL to urlpatterns:  path('blog/', include('blog.urls'))
 """
 from django.contrib import admin
+from django.conf import settings
 from django.urls import include, path
+from django.conf.urls.static import static
 
 from . import views