[bug] ObjectLocation admin doesn't work in readonly mode

[nemesifier]

When a user has only view permission, the map doesn't work because the JS fails (it was not tested in this scenario).

[devkapilbansal]

When a user has only view permission, the map doesn't work because the JS fails (it was not tested in this scenario).

I don't think it is due to the JS. If a user doesn't have change permissions, then these fields are not shown in ObjectLocation admin

I also found something in Django admin where we might found a possible fix 👇
https://github.com/django/django/blob/cf79f92abee2ff5fd4fdcc1a124129a9773805b8/django/contrib/admin/options.py#L674

[pandafy]

I also found something in Django admin where we might found a possible fix
https://github.com/django/django/blob/cf79f92abee2ff5fd4fdcc1a124129a9773805b8/django/contrib/admin/options.py#L674

That only affects ModelAdmin and not InlineAdmin.

I created a simple demo project with our use case and also posted in django-users mailing list for help.

Also, django-leaflet does not render map for view only permissions: makinacorpus/django-leaflet#85