Jessica Rinaldi/The Boston Globe via Getty ImagesSometimes you can tell a book by its cover. That’s certainly the case with former Harvard President Drew Gilpin Faust’s new memoir, Necessary Trouble: Growing Up at Midcentury. The last thing Faust wants her readers to care about is what she is best known for—being the first woman to lead Harvard.The front cover of Necessary Trouble is a close-up of Faust at 19, lying on the lawn at Bryn Mawr College looking intently through oversize glasses at wh