A grenade attack on a mosque in the troubled southern Philippines killed two people early Wednesday, authorities said, just days after a deadly Catholic cathedral bombing and a vote backing Muslim self-rule.The blast tore through the building as the victims were sleeping in the pre-dawn darkness on the insurgency-plagued island of Mindanao, which is home to the Philippines' Muslim minority.Blood-streaked prayer mats and shattered glass could be seen on the floor inside the mosque where h