It's said that necessity is the mother of invention and restrictions can often pave the way to creativity. This week's episode of Top Chef Masters ("Dietary Restrictions") forced the five remaining master chefs to do just that when they were faced with their toughest challenge yet: catering a lunch for actress/singer Zooey Deschanel and her friends. The only problem: Deschanel is a vegan with gluten allergies and an aversion to soy to boot. If they had any chance of pulling off this complicate