public ActionResult Configure()
        {
            var model = new ConfigurationModel();
            model.ClientKeyIdentifier = _facebookExternalAuthSettings.ClientKeyIdentifier;
            model.ClientSecret = _facebookExternalAuthSettings.ClientSecret;

            return View(model);
        }
        public ActionResult Configure(ConfigurationModel model)
        {
            if (!ModelState.IsValid)
                return Configure();

            //save settings
            _facebookExternalAuthSettings.ClientKeyIdentifier = model.ClientKeyIdentifier;
            _facebookExternalAuthSettings.ClientSecret = model.ClientSecret;
            _settingService.SaveSetting(_facebookExternalAuthSettings);

            return View(model);
        }