SARAH WHITE and MICHEL ROSE A third person was taken into custody in France in connection with a knife attack which left three dead in Nice on Thursday, a police source said on Saturday, as the government ramps up security efforts against possible militant attacks. An assailant shouting "Allahu Akbar" (God is Greatest) beheaded a woman and killed two other people in a church in Nice, in France's second deadly knife attack in two weeks. The third arrest took place on Friday and followed another that day and a previous one on Thursday, the police source said. At least two…