Symfony 2.2 is old

This project depends on Symfony 2.2, which is an old version near its EOL. Yet, the codebase works fine with the current LTS branch (2.3) as well as with the latest stable branch (2.4).

For the Console component, I changed the dependency to `~2.3` and locked the current stable release, 2.4.2. You also referenced the Symfony components Config and DependencyInjection, but as far as I can tell, you never use them. This is why I've removed them from composer.json.