WASHINGTON - Before joining Republican Mitt Romney's presidential campaign last week as a spokesman, Richard Grenell was a prolific - and inflammatory - voice on Twitter, posting biting commentary on subjects ranging from Newt Gingrich's weight to Michelle Obama exercising in the White House. No more. Since he joined Romney's campaign as foreign affairs spokesman, many of Grenell's most provocative musings on Twitter have been deleted in a cleanup that is the latest reminder of how social media has become a sideshow - and at times more - in the 2012 campaign. ...