Behat Tests, part 1

This is the first pass at adding Behat tests to the project.  As you can see, I created a branch for this.  If you want to create a branch and have me resubmit against that, I certainly can.

While there is only a simple basic feature in there, I thought it better to get the foundation in place and then build out the tests later.  

A few things to point out:
* The `mink-selenium-driver` was changed to be the `mink-selenium2-driver` in the composer.json file
* I added default passwords for the database users for dev environments.  We can always remove at a later date.
* The base_url parameter assumes that you've updated your hosts file to use `http://mentorapp.dev` as the development URL.

Feedback is welcome.  The sooner we get this merged, the easier it will be to incorporate before the main front-end work begins.