Cavan Sullivan is a phenom.
The 15-year-old is already a professional soccer player — a midfielder for the Philadelphia Union of Major League Soccer. And in three years, when he turns 18, his contract — which is reportedly worth $500,000 a year — has a clause that calls for him to be transferred to Manchester City.
On the sponsorship front, he’s an ambassador for Adidas and Raising Cane’s, a fast-food…