Add entrypoint for :woo/:clack

[inaimathi]

See the cl-handlers repo for how to do this. Basically, if we add make-app :: () -> (Request -> Response), we can make house applications compatible with woo and/or clack for more versatile serving. This seems like a fairly low-effort, unambiguous win. (If the low effort turns out to be false, don't do it :p )