Cleanup composer.json file

going to reroll

I kept name, description, license, and authors. The reason is that we use this repo for a package https://packagist.org/packages/dropsolid/rocketship#10.1.1 so it's possible to create with composer create-project.

Without these properties it will not work, so I suggest to manually cleam up them after you started a new project.

Automatically closed - issue fixed for 2 weeks with no activity.