By Denny Dyroff, Entertainment Editor, The Times Kirsten Agresta Copely The show on May 30 at the World Café Live (3025 Walnut Street, Philadelphia, www.worldcafelive.com) will be a little different than usual – in several ways. The headliner will be a solo artist. The main instrument will be a harp — which is more common with a classical concert and less common on the stage of a rock...