Fifteen years ago, few Americans other than farmers seemed to be thinking much about hens. Backyard chicken coops weren’t really a thing. No major animal rights group spent time or money on farm animal welfare. “Factory farming” wasn’t yet a catchphrase. No longer. In recent years, there has been a veritable revolution in public attention to eggs and the chickens that produce them. In the past two years, nearly 200 U.S. companies – including every major grocery and fast-food…