As far as I can see, the TravisCI build are actually not performing any testing.

This PR:

• fixes running test for all PHP versions
• performs a Drupal site installation test and site status report by
  • git cloning Drupal core
  • performing composer install of Drupal core
  • requesting drupal/console via Composer
  • performing drupal site:install
  • performing drupal site:status

This is obviously just my workflow... but it seems to work.