Great refactor of 2014. Closes #3.

[nevir]

Broke apart index.js into several components. server.js is the new entry point; and is responsible for setting up:

• A web server that...
  • ...consumes GitHub webhooks.
  • ...reports on the status of the server (for the load balancer).
• Queue, which watches for changes to the firebase queue, synchronizing ownership over queue items, and dispatching them to be processed.
• TestRunners are spawned to process commits. Most of the logic in index.js migrated here. Albeit flattened.