Self configuration workflow

[jace]

Setting up a HasGeek project on a new developer's computer is painfully unintuitive. Baseframe should have a /config handler that walks a user through this setup procedure and writes out settings/production.py files to the instance folder.

Hgapp's default handler for / should check for an incompletely configured app (possibly available only when Flask is in debug mode) and call Baseframe's config handler to take it forward.