Steps for Drupal form elements visibility

Hi,

I started using Behat for Drupal, my first scenarios involved verification of form element visibility (implemented through #states). I could'nt find an existing way to easily check the visibility of a form element. So I wrote a couple or steps to check for the (in)visibility of form element identified by their labels. This heavily relies on the default Drupal markup for form elements.

The code can be found at https://gist.github.com/pbuyle/7698675