(Reuters) — Aamir Khan, the Bollywood superstar with a conscience, says his next movie about a small town teenage girl who uses the Internet to become a singing sensation will be much bigger than his last film, India’s highest grossing ever. Khan, 52, plays a sleazy music producer in the film “Secret Superstar” and says he is second lead to teenager Zaira Wasim, playing a schoolgirl who defies her conservative Muslim family to pursue her […]