Management command to refresh permission objects.

[schwarzkrieger]

Closes #1137

[atodorov]

Needs changes, squash all commits together.

[atodorov]

Code review adjustments before squashing

Next time squash the commits as we're cleaning them up and working on the review.

[atodorov]

Drop the last commit because it makes things even worse and work to resolve items one by one. Ask if unclear.

[atodorov]

FTR the new Django 3.1 comes with remove_stale_contenttypes --include-stale-apps which looks like will resolve the removing of old objects.
https://docs.djangoproject.com/en/3.1/releases/3.1/#django-contrib-contenttypes

[atodorov]

There is update_permissions command from django-extensions which we already use to generate the model diagrams here: https://kiwitcms.readthedocs.io/en/latest/db.html

So before you continue spending more time on this issue, we need to make django-extensions into a production requirement and not only something used during development. Make this change in a separate PR.

The entry point will be update_permissions -v 2 and add that to the top of your handle() method via call_command.

django-extensions doesn't remove stale permissions so once the code here is approved it is better to contribute it upstream.

The need to update the Admin & Tester groups will still remain here after all of the changes.

[atodorov]

Rebase onto latest master to resolve the conflicts in docs.

[atodorov]

Also rebase to latest master which now uses Django 3.1.1

[atodorov]

Looks better than before, minor changes requested.

[atodorov]

Looks better now, a few nitpicks before I go into reviewing the rest.

[atodorov]

Overall looks good, aside from a few nitpicks the next thing this needs is tests.

The best way to tackle this is to first add tests for assign_default_group_permissions() in a separate PR from master where you don't have the changes; then add tests if necessary for the changes related to the new default params and afterwards work on tests for the management command itself.

[atodorov]

Rebase to latest master so we can see some test results

[atodorov]

Looks good, minor changes requested.