King Digital Entertainment, maker of the wildly popular mobile game Candy Crush, went public this morning on the New York Stock Exchange after raising about $500 million in an IPO that valued the company at about $7.6 billion. The number of people who play Candy Crush, along with the sales and revenue it generates, have already begun to slow down and taper off. If its going to succeed as a public company, it will need to find a new source of momentum. Zynga has made investors wary