Add ListenAndServe for transparent proxy support

[tj]

Instead of:

	if os.Getenv("LAMBDA_FUNCTION_NAME") == "" {
		log.Fatal(http.ListenAndServe(":5555", h))
	} else {
		apex.Handle(proxy.Serve(h))
	}

Just do:

log.Fatal(apex.ListenAndServe(":5555", h))

and let this pkg handle that