An accused teenage rapper pleaded not guilty today to making a bomb threat on Facebook he warned would eclipse the horror of the Boston Marathon tragedy and make him “famous.” Methuen High student Cameron D’Ambrosio, 18, who calls his rapping alter ego “Cammy Dee” in crude, profane YouTube videos, was ordered held without bail by Lawrence District Court Judge Lynn Rooney pending a May 9 dangerousness hearing after waiving his right to a bail argument. “I’m not in reality, So when u see me (expletive) go insane and make the news, the paper, and the (expletive) federal house of horror...