Import Nova "ironic" driver

Import the Nova "ironic" driver from the Nova review queue.
This Nova driver will not be present in the Icehouse release of Nova,
but is required for Ironic functionality and can be installed as an
out-of-tree driver.

Co-Author: Lucas Alvares Gomes <lucasagomes@gmail.com>
Co-Author: Devananda van der Veen <devananda.vdv@gmail.com>

Change-Id: I3351dee1a4b2dfb50317ce85dffe8012f0feca6c
Merge "Import Nova "ironic" driver"