public async Task<ActionResult> EditRole(EditRoleViewModel model)
        {
            if (ModelState.IsValid)
            {
                var identityManager = new IdentityManager();

                if (model.Id != null)
                {
                    var role = await identityManager.GetRoleByNameAsync(model.RoleName);
                    await identityManager.UpdateRoleAsync(role);
                }
                else
                {                    
                    await identityManager.CreateRoleAsync(model.RoleName);
                }
                
                await this.ApplicationDbContext.SaveChangesAsync();

                return RedirectToAction("Index");
            }
            return View(model);
        }