Improve Behat workshop

[MaXal]

The main idea of the workshop is to provide the seamless experience with the new features, meaning (no configuration, no terminal usage and so on). We provide the Vagrant box that has everything needed (PHP, Behat, etc.). You should avoid using anything besides that.

The fix should avoid behat --init, use Vagrant interpreter instead, and progress via MD file (instead of PHP comments)

Since configuration will be different for Docker there should be a fix for Docker branch as well.