Initial update to use the new code style

• You can now pass a custom --format parameter to format the output
• Improved error handling

codes now also works for apps that are not available in the US App Store

Fixed an issue that occured on startup because of an update of fastlane_core

Fixed codes --help command

You can now create URLs for your promo codes, thanks to @jhersh using 👍

codes 5 --urls

Updated fastlane_core dependency

Generate promo codes for your apps