Feature: Kiosk mode

[brianwarner]

Right now, Facade is mostly intended to be run internally, behind a firewall. The authentication is pretty basic (see issue #16), so this should certainly be addressed before putting this out on the open web.

An alternative, though, would be to have a read-only kiosk mode. The simplest way to do this (I think) would be to cache the pages as boring old HTML files, which could then be periodically transferred to a public server. Every time facade-worker.py runs, it would overwrite the old cached files. This has the advantage of being completely non-interactive and should also be quite fast. But I'm open to ideas.