All Miles Scott wanted to do was to put on his Batman costume and fight crime on the grimy streets of Gotham City. Miles, a 5-year-old leukemia patient, got his wish on Friday, and his heroism earned him a pat on the back from President Obama. “Way to go, Miles. Way to save Gotham,” the president said in one of his first posts on Vine,a social media site that loops six-second videos uploaded by its users.