Suffolk University President Margaret McKenna and Board of Trustees head Drew Meyer are both stepping down in a stunning end to their standoff that has roiled the Boston institution for the past week.In a joint statement, McKenna and Meyer said trustees voted to pass a resolution reshaping the board and starting a new search for president "in the best interest of the insitiution."Meyer will quit after his term expires in May and McKenna will step down after her successor takes over by the start of the 2017 academic year.