Americans may be using less toilet paper, if Sheryl Crow has her way. The singer, who is crossing the country on a biodiesel bus with producer Laurie David, proposes limiting toilet paper use as one solution to global warming, according to a Washington Post report. "I have spent the better part of this tour trying to come up with easy ways for us all to become a part of the solution to global warming," she wrote April 19 on the Biodiesel Bus blog, according to a report by the Washington Post. "Although my ideas are in the earliest stages of...