public static Negotiator Success(this Negotiator negotiator, object response = null, MetaData metadata = null)
 {
     var negotiate = negotiator.WithStatusCode(HttpStatusCode.OK);
     return negotiate.WithModel(new AcgResponse(response, metadata ?? new DefaultMetaData()));
 }
 public static Negotiator Success(this NancyModule module, object response = null, MetaData metadata = null)
 {
     return module.Negotiate.Success(response, metadata);
 }