Add initial cut at 404 page

This seems to work fine for most 404 URLs. The problem is the case where the URL matches one of the other patterns, but doesn't match the data.

For example:

* http://localhost:1754/xyz/blah -- 404 page!
* http://localhost:1754/half-ogre/qedxxx -- NADA!

What's the best approach for a dispatcher to hand it off to the next one?