[experimental] good_job

[jrochkind]

Testing good_job ActiveJob queue. Ref #1245

• admin dashboard IS enabled!
• development mode IS set up to by default use good_job in async mode, instead of rails async. test mode is still using Rails job harnesses.
• Procfile does NOT yet have workers set up for good_job, there are still some things we need to figure out
• resque has NOT been removed, if we were really switching over, we'd remove it and all references to it

Using good_job in development

While this isn't (yet) set up to run good_job workers on heroku, you can totally test out good job in dev.

By default, this branch is using good_job in "async" mode, meaning the workers are actually threads in the Rails process. You can take a look at the queue admin page this way though -- it's pretty snazzy.

If you want to run in development with actual good_job workers, you can do that too!

1. Launch as GOOD_JOB_EXECUTION_MODE=external rails server (good_job by default looks at that env var, and others, it isn't something we set up)
2. In another terminal window, just do bundle exed good_job to start a worker with default config. (You can also pass various things on the command line to control worker behavior)
3. If you want to open a console in which you might manually enqueue jobs, GOOD_JOB_EXECUTION_MODE=external rails console is probably a good idea.