Rock Hill and Winthrop University are about to become the hub of presidential politics. For a day, anyway. On Friday, the campus located 25 miles south of uptown Charlotte - and across the state line - will welcome the chief protagonists from last month's Benghazi hearings (S.C. Republican Congressman Trey Gowdy and Democratic front-runner and former Secretary of State Hillary Clinton) as well as a slew of other notable politicos and media types. The headline event is an MSNBC presidential...