Some Park Slope moms have a new romantic obsession besides best-selling bondage book “Fifty Shades of Grey.” “Loads of moms are all in a flap about sightings of gorgeous Jack Davenport with his cute son,” says one smitten resident about the “Smash” star who apparently lives in the ’hood. Glimpses of dashing Davenport has Facebook on fire with women swooning, “Just spotted Jack Davenport in the local playground. Bet you wish you’d been there, Brooklyn girlies!”