This year’s class going into the Rock and Roll Hall of Fame includes-pop star Madonna, folk singer Leonard Cohen, rocker John Mellencamp, British pop band The Dave Clark Five and instrumental group The Ventures. Madonna and John ‘Cougar’ Mellencamp share the same bit of my memory-I even went to a Madonna concert in Texas Stadium where she bitched and moaned about how hot it was in Texas in the summer. Leonard Cohen is not a name that is ringing any bells-but maybe if I heard a couple of songs I’d know who he is. But the big shocks on the…