add test files

[builder-demo] / src / roo-gtksettingsApplication.vala

public class roogtksettingsApplication : Gtk.Application
{
        public roogtksettingsApplication (string[] args) 
        {
                Object(
                        application_id: "org.roojs.roo-gtksettings",
                        flags: ApplicationFlags.FLAGS_NONE
                );
        }
}