uses upstream's stage4 images, includes all the needed bells and
whistles for openstack on kvm.
Change-Id: Ibca43173c30c2a74a73a2e2d9dd6d6d832c62694
Closes-Bug: 1530911
In order to add more flexibility to the vm and bootloader
elements, split the functionality in two different ones, and
make vm depend on bootloader element.
This will allow to construct more elements that depend on
bootloader, and develop both elements independently.
Change-Id: Iad2503b7b8fe53b768a3bc79e4cb839700fbd747