private async void PasswordBox_KeyDown(object sender, KeyRoutedEventArgs e)
        {
            bool success = false;

            success = CustomerLogic.Login(UsernameBox.Text, PasswordBox.Password);

            if (e.Key == Windows.System.VirtualKey.Enter && success)
            {
                Frame.Navigate(typeof(CustomerListPage));
            }
            else if (e.Key == Windows.System.VirtualKey.Enter && !success)
            {
                MessageDialog logincreation = new MessageDialog("Wrong username or password", "Login failure");
                {
                    logincreation.Commands.Add(new UICommand {
                        Label = "OK"
                    });
                }
                await logincreation.ShowAsync();
            }
        }
        private async void LoginButton_Click(object sender, RoutedEventArgs e)
        {
            bool success = false;

            success = CustomerLogic.Login(UsernameBox.Text, PasswordBox.Password);


            if (success)
            {
                Frame.Navigate(typeof(CustomerListPage));
            }
            else
            {
                MessageDialog logincreation = new MessageDialog("Wrong username or password", "Login failure");
                {
                    logincreation.Commands.Add(new UICommand {
                        Label = "OK"
                    });
                }
                await logincreation.ShowAsync();
            }
        }