Israeli media firm Keshet, the company best known for transporting Homeland to the U.S., has acquired a majority stake in British production group Greenbird Media. The deal was unveiled at the In-TV conference in Jerusalem, which kicks off today. The move is Keshet's largest international acquisition and gives it a major presence in the UK, with production companies including Tuesday's Child, the company behind ITV and Fox's You're Back In The Room, and Crackit…