private async void Logout_Tap(object sender, System.Windows.Input.GestureEventArgs e)
{
ServerHelper serverHelper = new ServerHelper();
await serverHelper.Logout();
using (DataBaseContext db = new DataBaseContext(DataBaseContext.DBConnectionString))
{
db.DeleteDatabase();
}
IsolatedStorageFile storage = IsolatedStorageFile.GetUserStoreForApplication();
storage.Remove();
NavigationService.Navigate(new Uri("/LoginPage.xaml", UriKind.Relative));
}