Police are crediting the work of their K-9 partner Vader in a breaking-and-entering arrest yesterday afternoon in Boston.The suspect, Sam Hess, 28, of Boston was last seen climbing onto a fire escape and entering a Boylston Street building through a second floor window yesterday morning, police said.A Boston police K-9 handler and Vader entered the building and located Hess hiding inside a crawl space under a first floor stairwell, cops said.