Feature-wish: add php-version to composer-definition as requirement - add infos about the licence

[Padina42]

1. If you build a grid for an extension, the composer.json should include a requirement about the php-version. 'make' should use the version of the running phy-system as value. It would helpful for updates in the future.
2. After asking the extension should include the GPL-licence, the MIT-licence or nothing into the code (composer-json & and referenz-code). The developer should think about this at this early stage.