Django 2.2 upgrade

[umgelurgel]

More of a long-term goal, but decided to have a look at what would be required to get there. Some of the modules used don't currently support Django 2.0:

• django-cms
  • Planned for the 3.6 release, no date scheduled.
• django-authority
  • Unmaintained.
• django-filer
  • PR fixing waiting to be merged: Adding support for Django 2.0/2.1 django-cms/django-filer#1096

In the meantime, the deprecation warnings coming from the application itself can be fixed.

[matrixise]

For django-authority there is a PR for the support of django 2.2

[matrixise]

And for Django-filer, the PR has been merged in November 2018

[umgelurgel]

I think it would be a good idea to get the tests fixed, then retire the old code and only then do the upgrade.

[umgelurgel]

I am looking forward to getting rid of all the deprecated in django 2 warnings though :D

[aramboi]

We should probably update to the latest LTS version of Django 2.2 and only use LTS versions in the future to minimise maintenance over time.

Support for Django 1.11 security updates ends April 2020, a few months before the conference, so while not urgent this is a must as far as I can see.

We should look into upgrading by the end of the year. I think all our dependencies will catch up by then. 🤞

[umgelurgel]

This is going to have to be done in multiple steps, as some libraries are removed in the process, have dependencies in migrations.

1. Remove the cms_utils models, add a migration that removes them from db.
2. Remove the cms_utils migration history, the migration files and the markitup dependency.
3. Upgrade the rest of the codebase to django 2.2.

I've got a WIP branch that tackles point 3, branches for the first two points will be created as soon as the initial staging deployment takes place.