public ActionResult Details(int?id)
        {
            if (id == null)
            {
                return(new HttpStatusCodeResult(HttpStatusCode.BadRequest));
            }

            var categoriaBo = new CategoriaBo();
            var categoria   = categoriaBo.Mostrar(id.Value);

            if (categoria == null)
            {
                return(HttpNotFound());
            }
            return(View(categoria));
        }