Rocinha slum called vital for World Cup, Olympic security
                                
                                
                                    (Newser) -
                                    Upwards of 2,000 members of the Brazilian police and military, backed by armored vehicles and helicopters, swept through Rio's biggest slum before dawn today, in the biggest anti-gang action  since last November , reports the  AP . But unlike the previous raid, which was precipitated by a rash of gang...