public ActionResult Edit(RoleModel model)
 {
     if (ModelState.IsValid) {
         RoleProvider.Update(model);
         return RedirectToAction("Index");
     }
     return View(model);
 }
 public ActionResult Add(RoleModel model)
 {
     if (ModelState.IsValid) {
         RoleProvider.Insert(model);
         return RedirectToAction("Index");
     }
     return View(model);
 }