SEATTLE — Jones Soda Co. takes the idea of a liquid diet to a new low. How does Green Bean Casserole Soda strike you? And how about an aggressively buttery-smelling Mashed Potato Soda? Even the creators of the fizzy concoctions at this small Seattle soda company can hardly stomach the stuff. But last year's unexpected success of the Turkey & Gravy Soda means another round of bizarre food-flavored soft drinks. As an added bonus — they're calorie-free.