public ActionResult EditUser(string id) {
            if(id == null) {
                return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
            }

            var user = UserManager.FindById(id);

            if(user == null) {
                return HttpNotFound();
            }

            ViewBag.DefaultRole = UserManager.GetRoles(user.Id)[0];
            var roles = new SelectList(db.Roles.ToArray(), "Id", "Name");
            var editUser = new EditViewModel() {
                Id = user.Id,
                UserName = user.UserName,
                Email = user.Email,
                PhoneNumber = user.PhoneNumber,
                Roles = roles,
                IsActive = user.IsActive
            };

            return View(editUser);
        }
        public async Task<ActionResult> EditUserConfirmed(EditViewModel model, string Role) {
            if(!ModelState.IsValid) {
                return RedirectToAction("ListUsers", "AdminPanel");
            }

            var user = UserManager.FindById(model.Id);
            if(user == null) {
                return HttpNotFound();
            }

            user.UserName = model.UserName;
            user.Email = model.Email;
            user.PhoneNumber = model.PhoneNumber;
            user.IsActive = model.IsActive;
            UserManager.RemoveFromRoles(user.Id, UserManager.GetRoles(model.Id).ToArray());
            UserManager.AddToRole(user.Id, RoleManager.FindById(Role).Name);
            await UserManager.UpdateAsync(user);
            await db.SaveChangesAsync();
            return RedirectToAction("ListUsers", "AdminPanel");
        }