Experiment with workers

I've been playing around with doing the feed fetching/parsing in the delayed job queue instead of the scheduler (to address costs mentioned in #259). The `3.times` spawning workers stuff seems Bad, but it has been running okay for me. The whole running DJ in a unicorn worker is definitely not the preferred method.

There is some legwork of setting your app url and forcing the dyno to wake up before we queue (otherwise the dyno would be idle and not process...I think, didn't really play with it too much).

Here is my dyno usage for the scheduler process after deploying this branch on Sept 17
![image](https://f.cloud.github.com/assets/56947/1241246/634a1d1c-2a19-11e3-8170-6e41fc197ccc.png)