The theme music from Harrison Ford's movie 'Air Force One' blared over loudspeakers in a rural Tennessee airport hangar, and minutes later a less presidential noise wafted over a hot mic. 'Get in the plane and go home. It's over there. Go home.' That was Donald Trump, the Republican presidential front-runner, telling his newest endorser Chris Christie in front of 12,000 people exactly where to go and how to get there. Christie had just sung The Donald's praises following the dramatic entrance of his plane in a stunt the campaign invented a month ago in Dubuque, Iowa. And more importantly,...