private async void BtnAddCat_Click(object sender, RoutedEventArgs e)
{
var name = NaamCat.Text;
if (NaamCat.Text.Length != 0)
{
await cvm.AddNewCat(name);
NaamCat.Text = "";
}
else
{
MessageDialog md = new MessageDialog("Name can't be empty");
await md.ShowAsync();
}
}