Also:
* Refactored the specs organization to make the resoning behind simplier,
introducing the idea of an artifact subject that it wraps the
interactions with the platform.
* Add methods to destroy, bootstrap and halt a list of machines either all of them or the ones listed under a given platform name.
* Introduced more clear namespacing in the rakefile.
* Updated the list of available platforms for acceptance testing, including latest ubuntu, oel, fedora, debian and suse versions
Fixes#5350