In celebration of Atari’s 40th Anniversary the company is giving away all of the 100 games included in its Atari’s Greatest Hits iOS app for free. Normally available as in-app purchases at $1 each of $10 for the entire set, for today only users will be able to download Atari 2600 classics such as Asteroids, Centipede, Pong, Battlezone and more. An updated version of the app has been released on the App Store for the 40th anniversary special.…