From a blog in the AtlanticMichelle Obama was in top reassuring-mom mode Friday morning, as she delivered the keynote speech at the Partnership for a Healthier America’s annual summit.“I want to be very clear: You all did this. Not me,” the first lady told the hundreds of anti-obesity crusaders crowded into the ballroom of the Renaissance Hotel in downtown Washington. “I might have added a little sparkle of publicity, but you all did the work.”Launched in 2010 in conjunction with her L …