SAN FRANCISCO (Reuters) - A 97-year-old great-grandmother who quit school in the fourth grade to help her sharecropper parents pick cotton will receive a high school diploma after going back to school to study computers. "I wanted to do this when I was a young lady but my parents just couldn't afford it," Gustava Bennett-Burrus said in an interview on Friday. "I long wanted to go back." She started taking computer classes at Richmond High in Contra Costa County in Northern California in January and is set to receive an honorary high school diploma next week. "In my mind I...