CLEARWATER, Fla. — To Bo Porter, intensity is a light switch. If the Astros never flip the switch on, the young rebuilding club will never stand a chance in 2013. And if the Astros wait until midway through the regular season to see if their light even burns? “You can walk into the room and then you hit the switch and the bulb (can) be blown,” Porter said. So Porter’s flipped the switch himself. The Astros’ new energy began last October, when he officially took over the worst team in baseball two years running. The buzz has been felt since his club’s spring training started last week in Kissimmee, Fla. [...]