Grab instance for migration before updating usage

Updates _update_usage_from_migrations so that it grabs the instance
associated with a migration before updating usage.

Bug 1163622

Change-Id: I64acef912ae71ea5c7fb66e9fcaafe5750c63eaf
(cherry picked from commit a574af21f81e12ea5fd48ad50bd0535d08fcda24)
Add missing snapshot image properties for VMware Hyper.

Fix bug #1174199

Change-Id: I50929ed2e66052a37bb5a94cd3863baaebda1e28
(cherry picked from commit 2872db90137612c067617eea30717dcd676fbfc0)
Fix baremetal get_available_nodes

Baremetal driver get_available_nodes was incorrectly returning only a
list of unprovisioned nodes, leading update_availabile_resources to
sometimes delete a baremetal node that had an instance provisioned
to it -- sometimes even while the provisioning was still in process.

Fix bug 1174952

Change-Id: I4f08a2f6539a5b6cd12245ac6b4dc308767ae0cd
(cherry picked from commit 75568fe6309d0e89f829bc15f14536506e58a152)
Merge "Fix baremetal get_available_nodes" into stable/grizzly
Merge "Grab instance for migration before updating usage" into stable/grizzly
Merge "Add missing snapshot image properties for VMware Hyper." into stable/grizzly