Nick Cassini, a former pro golfer on the PGA Tour, knows a thing or two about branding.  The senior vice president of sales and marketing at IMI Worldwide Properties is also-not incidentally-the son of Count Igor Cassini (aka Cholly Knickerbocker, the famed author and Hearst gossip columnist) and the nephew of iconic fashion designer Oleg Cassini.  So when the beloved Viceroy Anguilla, with its pair of powdery beaches and Kelly Wearstler interiors, was reflagged as Four Seasons last fall, the athletic 38-year-old-tasked with overseeing residential sales for the Four Seasons Resort and Residences Anguilla-knew the move would be a branding bonanza.