PORT-AU-PRINCE, Haiti (AP) - Enraged supporters of ousted President Jean-Bertrand Aristide armed themselves with machetes, guns, rocks and bottles and roamed a downtown slum, threatening to behead foreigners after U.N. peacekeepers and Haitian police arrested dozens of people Wednesday. As gunfire crackled and two helicopters roared overhead, peacekeepers in armored personnel carriers moved into Bel Air, trying to put down a campaign by Aristide loyalists who have carried out gory beheadings in imitation of Iraqi insurgents. Wednesday morning, the headless body of a man lay in the street in La Salines, a seaside slum. Last week, three police officers were...