Police say they have arrested a man who was wanted in connection with two robberies at businesses in downtown Boston last weekend. Rongit Whistleton, 54, of Boston, was arrested on Friday on Boylston Street on a probation violation out of Suffolk Superior Court for unarmed robbery, rape and kidnapping. Further investigation by police detectives determined that he was also a suspect in two commercial robberies that occurred on Sunday at businesses on Washington and Staniford streets.