composer setup

[bnomei]

even if this repo is not final or you will not put it onto packagist yet i still wanted to contribute in PRing a composer setup.

• index.php => config.php
• composer.json + index.php with autoload
• gitignore file
• run composer zip to create zip for github

thanks for your great work on the builder plugin!

[TimOetting]

Thanks for you contribution. The repo now uses this asset pipeline: https://github.com/medienbaecker/kirby3-boilerplate