Create a single domain per run

We used to create a Node domain per step/step definition. It caused issues with 3rd party librairies like Protractor.

Squashed commit of the following:

commit 496e38519ef75cff6537245302b93c69c4a33696
Author: Julien Biezemans <jb@jbpros.com>
Date:   Tue Dec 23 23:20:04 2014 +0100

    Fix tests

commit 523fce855f53e3ce059aaf6b2320f5a4be043627
Author: Julien Biezemans <jb@jbpros.com>
Date:   Tue Dec 23 15:37:46 2014 +0100

    WIP