private async void LoginStatusDialog(String login, String mdp)
        {
            String content;

            if (bdd.checkCredentials(login, mdp))
            {
                content = "Vous êtes connecté";
            }
            else
            {
                content = "Erreur de login";
            }

            ContentDialog dialog = new ContentDialog
            {
                Title           = "Exercice 2",
                Content         = content,
                CloseButtonText = "OK"
            };

            ContentDialogResult result = await dialog.ShowAsync();
        }