Be sure to support remote runners

[domenic]

Currently the runner is centered around firing up a runner on the same computer as the CLI. It'd be cool to have a Surface or just another PC, and send test-blobs over to that.

That way your screen doesn't get taken over to run the tests, and you can either leave it in GUI mode to get a nice dashboard (e.g. with your Surface propped up next to your dev computer), or you can just have it send things back to the CLI on your local computer (see #3).

This is related to #1. It might involve splitting the runner from the server/CLI (i.e. splitting lib/ from src/).