Replace Django with TwistedWeb, closes #12

Since AutobahnPython pulls in Twisted anyways, use the TwistedWeb server
to serve the static content instead of depending on Django. This server
can be run under the same reactor as the Autobahn websocket server so the
whole application can now be brought up with a single twistd command:

twistd -y cah.tac

(Use -noy instead for development)

Since that works, BOOM HEADSHOT to Django, which has had its configuration
files removed.