Use different libvirt drivers for launch and migration.

When doing a pure launch we want to restrict the possible image
backends to only qcow2. To support this a libvirt driver is created
then modified so that its image backend will only return qcow2. For
migration we want to support the full list of available backends.

Change-Id: Ifec60b1be12aba9c2ce8973d71f7a989b7f6b9bc
Stay on same dashboard's instances table after actions

The success_url of the workflows was previously set to
the full reverse URL path for the nova instances table,
but this meant that after performing an action in the
syspanel instances table the browser would jump back to
the nova dashboard. Since the success_url can be a module
path or a real URL, setting it to "." causes the browser
to be redirected back to the current page.

Change-Id: Ia0b0709f251c1fc791b732ca21cea1e37ba2ff9a
Merge branch 'stable/essex' into stable/folsom

Change-Id: I1e31954da5cedd053418e9a518d09bf3937151b6
Merge "Stay on same dashboard's instances table after actions" into stable/folsom
Merge branch 'stable/folsom' into master-folsom-merge

Change-Id: I9bc0a2b2c85dcea0844d40ab822eb14b28bfef0a