Add a Drupal distribution configurator

From https://dri.es/a-drupal-distribution-configurator, yesterday:

Today, Commerce Guys shared a new initiative for Drupal Commerce. They launched a "Drupal Commerce distribution configurator": a web-based UI that generates a composer.json file and builds a version of Drupal Commerce that is tailored to an evaluator's needs. The ability to visually configure your own distribution or demo is appealing. I like the idea of a Drupal distribution configurator for at least three reasons: (1) its development could lead to improvements to Drupal's Composer-based workflow, which would benefit all of Drupal, (2) it could help make distributions easier to build and maintain, which is something I'm passionate about, and last but not least, (3) it could grow into a more polished Drupal evaluator tool.