Ne-yo and his wife Crystal Renay have welcomed their third child together! The couple named their second son  after his father: Shaffer Chimere Smith, Jr., or “S.J.” for short. (Ne-Yo is the singer’s stage name.) S.J. arrived via an emergency C-section, weighing in at 6lbs., 8oz., and measuring 19 inches.  Despite his dramatic arrival, the singer’s rep confirmed to…