A pumped-up Herman Cain is promising a rock ’em, sock ’em takedown of Republican presidential rival Mitt Romney, saying he’s already got the Bay State governor on the run and can deliver a knockout at Tuesday night’s debate because voters “can’t get excited about (Romney’s) leadership.” “He got a little defensive last time, so he knows Herman is going to come after him,” Cain said during a phone interview with the Herald yesterday. “We are in a contest here. We are in a battle.” Cain, who has surged to the front of the crowded Republican presidential pack, already locked on...