Return non zero exit code when there are magic number in the codebase

[raphaelstolt]

Might need integration tests verifying the two exit return codes. Also an Added entry to the CHANGELOG.md should be included here already so you don't have to add it when releasing.

[phaldan]

If you return the exit-code in the execute method instead of calling exit directly, the BaseCommand will do the rest for you. Then you could test the execute method directly.

[povils]

Thanks guys for suggestions!