Mother’s Day is just around the corner, and this week, during which all eyes are on the accomplishments of the president, we look at his mother, Stanley Ann Dunham.  A teenage mother, she married and divorced twice, had two children, and eventually went on to earn a PhD and work in international development.  New York Times writer Janny Scott has written a new, comprehensive biography of Dunham called “A Singular Woman: The Untold Story of Barack Obama’s Mother.”