Concurrency Wins

Fixes #7.

Makes concurrent test handling much better.

• Handle tests as part of a jobs queue.
• Support jobs queue in-process, but recommend as its own service.
• Add docker-compose file including queues service setup.
• Don't hold onto and re-use the same Database for the duration of the long-lived testing process; instead recreate a database once per status update as if handling new requests each time.
• Put blocking tasks in test running process on packthread threads using the NIO thread pool.