In backbone, it's possible to provide an isNew() function that relies on attributes other than the default id. This poses a problem for deletion in the Route server as destroy() checks to make sure a model isn't new before proceeding. If any key attributes used by a custom isNew() function are missing, the destroy will be aborted.
The most straight-forward remedy would be to ensure that all model attributes are available before destroy() is called. It's currently unclear to me whether it's safe to use the req.body provided by the client or if the server should call fetch.
Set model body during a DELETE request. Refs #70.