Mayor Adrian Fenty has long been a health-nut, and his family has long owned local sports store Fleet Feet on Columbia Road NW. But if you mix the two, what do you get? A pack of angry Republicans. Today we received a press release from the D.C. Republican Committee decrying Fenty’s choice of apparel in a new ad to promote the District. The ad, part of a new $2 million branding campaign launched by the…