Added rqcronjobs management command to easily manage cron jobs from settings file

[lechup]

Idea here:
#159 (comment)

• created rqcronjobs management command
• added some tests
• added some documentation

To verify:

• does it make sense to use lazy for RQ_CRONJOBS
• are all variable names/function names sane?
• should we remove onlyt cronjobs while iterating over scheduler or it's ok to just remove eveything? how to check that?

[selwin]

Thanks for the PR, @lechup . I think it's better if we implement a better way (one that doesn't require iterating through all jobs) to check whether a certain job is already scheduled.

This should be implemented in rq-scheduler so everyone can benefit from that (especially now that rq-scheduler supports cron jobs.

[selwin]

I'm still thinking of how best we should implement this, so suggestions are welcome.

[lechup]

Hm... Yeah. I only use cronjob in my projects (no enqueue_in/at) so iterating and by default remove old and add new jobs was the KISS'est sollution for me. For sure I should add a check there to filter only cron jobs... Or create a get_cronjobs() on scheduler API and use that one here in management command?

I guess by saying It should be implemented in rq-scheduler you mean some kind of generic API that would enable cronjobs management by setting file? That one I proposed is django one so I thought django-rq would be a better place...

I'm also open for discussion and proposals :)