Blake Shelton and Luke Bryan playfully traded barbs via Twitter — and Gwen Stefani was dragged in the middle of it.Shelton, 44, tweeted a doctored photo on Monday, August 17, of Bryan, also 44, doing a TV interview with a chyron that read, “Study Finds Falling Asleep at the Wheel Linked to Luke Bryan Music.” He captioned the image, “Wow! Just catching up on the news… Shocking! I have noticed some fatigue when @lukebryanonline comes on..”The “One Margarita” singer was quick to clap back, jokingly