Merge branch 'rbd-ephemeral-snapshot-havana' of https://github.com/jdurgin/nova into merge-rbd-cloning

Conflicts:
	nova/tests/virt/libvirt/test_imagebackend.py
	nova/virt/libvirt/driver.py
	nova/virt/libvirt/imagebackend.py
	nova/virt/libvirt/utils.py

Closes-rally-bug: DE1186
Implements: rally-task: TA8264
Not-in-upstream: true