Adding 'hello world' Behat test as a small example of BDD integration

A simple behat integration to encourage BDD for the skeleton application.

This is just a WIP since I myself am new to all this.

I strongly believe the end user of the skeleton application should be well aware of the separation that has to be done between end-to-end integration testing (this kind) and unit testing (for module code).

Providing a `make test` similar setup would be a benefit.

I'm hereby proposing to ship unit tests with the modules (`Application` module as a start) and this thing with the `ZendSkeletonApplication`.

Discuss!