Create a proxy server using cloudcfg.  Useful for demos

So it would look like this
```
type handlerWithError  func(w http.ResponseWriter, r *http.Request) error
func (h *handlerWithError) ServeHTTP(w http.ResponseWriter, r *http.Request) {
    if err := h(w, r); err != nil {
	w.WriteHeader(http.StatusInternalServerError)
 	w.Header().Add("Content-type", "application/json")
 	status := api.Status{
 		Status: fmt.Sprintf("internal error: %#v", err),
 	}
 	data, _ := json.MarshalIndent(status, "", "  ")
 	w.Write(data)
    }
}
```
And each handler can be setup with `.handle(handlerWithError(handleFoo))`, returns `error` and they would get handled by `ServeHTTP`, of course if you ever have only 1 handler, that's not really useful.