text: Armored Vehicles Mass at Gaza Border JEBALIYA REFUGEE CAMP, Gaza Strip - Armored vehicles massed on Gaza's border Friday after Israel's security Cabinet approved a large-scale military operation - dubbed "Days of Penitence" - to stop Palestinian rocket fire.    Defense Minister Shaul Mofaz had ordered troops to "exact a price" from the militants, security officials said, after a Hamas rocket killed two children, ages 2 and 4, in an Israeli border town...