Nathaniel Adams Coles was 15 when he dropped out of Wendell Phillips Academy in Chicago to pursue a career in music. Three years later, in 1937, he managed to sell his first song, a catchy tune called “Straighten Up and Fly Right,” for fifty dollars. Coles died of cancer in 1965, but just the other day his daughters completed a sale of his music catalog to Iconic Artists Group for a sum believed…