repo needs instructions for API keys for youtube, flickr, drive, etc

[plural]

right now, config/demo-playlist.json plays a bunch of stuff that doesn't work unless you go and configure API keys. The docs for that are bad and the feedback for it is bad.

In addition to better instructions, the modules should have a way to say they are unhealthy and be skipped by the server if their API keys aren't available, for example.