It doesn’t take a background in PR or advertising to know that Pinkberry, Red Mango, and other similar frozen yogurt brands are, at the moment, red hot. For those of you unfamiliar with the product, the concept is simple: take low or non-fat yogurt, freeze it, and top it off with your choice of fresh fruits or other toppings. “The menu is so simple, that it is easy for someone without history or experience in…