By Darlene Superville, Associated Press March 6, 2015   First lady Michelle Obama speaks at the annual Building a Healthier Future 2015 summit in Washington, Thursday, Feb. 26, 2015. (AP Photo/Jose Luis Magana)     WASHINGTON, D.C. (ASSOCIATED PRESS) — Michelle Obama said Thursday that the U.S. has undergone a “culture change” in the five […]