To get all available options in json for each command, `composer help <command> --format=json` can be used. This allows us to simply parse the output and dynamically find out if an option is available. Neat!
Fix `changed` status that always returns False with composer.
This [previous PR](https://github.com/ansible/ansible-modules-extras/pull/61) had fixed the issue but because of a [Composer recent change](cb336a5416) stderr is now used for reporting information meant for humans while stdout is more for the output of the command.
This PR would definilty solve this issue.
