Now that the stage is set for the new late night network TV wars, NBC’s Jimmy Fallon and ABC’s Jimmy Kimmel had a message for their new rival soon to take over for Letterman at CBS: Congratulations Stephen Colbert. The two posted gracious messages to Colbert on Twitter after it was announced that he’d be taking the reigns of the Late Show when Letterman retires next year. Behind the scenes the networks may be on the verge of a new ratings rivalry, but at least on Twitter, Fallon and Kimmel seem excited to welcome Colbert to the competition …