Get biographies, policies, and other info about the major 2020 presidential candidates — including Cory Booker, Pete Buttigieg, Julian Castro, John Delaney, Tulsi Gabbard, Kirsten Gillibrand, Kamala Harris, Amy Klobuchar, Wayne Messam, Beto O'Rourke, and Bernie Sanders — through personal interviews and original reporting from Yahoo Finance.