Exit swamp, enter luxury. Former President Barack Obama and First Lady Michelle Obama are eyeing an Upper East Side apartment at 10 Gracie Square, a tony co-op building near East End Avenue that’s been a home to the likes of Gloria Vanderbilt and real estate scion Eric Rudin. If the Obamas make a deal, it would be their second home purchase of the year, after picking up a Kalorama, Washington, D.C., manse for $8.1 million […]