Scheduled post engine

[bjacobel]

I hate Buffer and so does everyone on staff. It does a bad thing and it's bad at it. But, sigh, it's a necessary evil for getting people to read our stuff.

• Replace Celery with rq and rq-scheduler
• Implement rq-dashboard
• Implement Facebook API tie-in that can post an article
• Implement Twitter API tie-in that can tweet an article
• Implement CMS controls for scheduling posts about an article
• Extensively test
• Extensively document

Labeled with "systems" because Celery and because everything Celery is waay harder than it needs to be so the odds of having to dig into that are high.