Move cron jobs to django-q scheduled tasks

[saadmk11]

Reference #961

TODO:

• Remove References to cron job (we can either do this on this PR or try the new changes out first)

[jefftriplett]

Did you want to use this for something? (Not seeing it referenced in case it's used in an unobvious place.)

[saadmk11]

This is required by django-q2 to parse cron expressions. https://django-q2.readthedocs.io/en/master/schedules.html#django_q.Schedule.cron

[jefftriplett]

Looks good to me. I left the note about croniter in case you were wanting to use that in settings.

[jefftriplett]

@mashrikt looks great. We can adjust cron in a new PR. I'll hold off on deploying

[saadmk11]

We can adjust cron in a new PR.

Do you mean the cron schedule?

---

How do we setup cron jobs on the current production servers? I don't see any references to it on the codebase other than this:

djangopackages/fabfile.py

Lines 127 to 131 in 024ece9

	def cron():
	with env.cd(env.project_dir):
	docker_compose("run django-a python manage.py import_classifiers")
	docker_compose("run django-a python manage.py import_products")
	docker_compose("run django-a python manage.py import_releases")

Do we set this up manually on production server by modifying the crontab file?