The Prancercize Lady is one small reason to sorta like John Mayer for the next 4 minutes and 31 seconds. Probably preferring to be called by her real name, Johanna Rohrback does what she does best and prances about a suburban street to Mayer’s new song Paper Doll, thought to be about Taylor Swift. Yes, folks — after the Harlem Shakes and Gangnam Style, welcome to your new summer shimmy…