added api versioning example using the FOSRestBundle VerisonListener

that is what we are doing .. however the media types with all parameter permutations need to be registered and I am wondering if we could not find a solution so that not all permutations need to be registered (https://github.com/FriendsOfSymfony/FOSRestBundle/blob/master/Util/FormatNegotiator.php#L130).