Use install_venv_common.py from oslo.

This syncs install_venv_common.py from oslo and reworks the
tools/install_venv.py script to use the new library.

Change-Id: I020eae1ec9e3a6aae0ecc7825c0ef723ab247f39
Refactor libvirt volume driver classes to reduce duplication

Most of the libvirt volume driver class repeat the same setup
of the vconfig.LibvirtConfigGuestDisk() instance. Create a
more suitable base class to hold this common setup and simplify
all the other subclasses accordingly

Change-Id: I9a5a70ccf88a1e55cdb120c8c6d29e6847774691
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Remove unnecessary deserializer test

Fixes bug 1109166

Change-Id: Icb2d7a613103e130e83e054864bfdbc599747537
Merge "Remove unnecessary deserializer test"
Merge "Refactor libvirt volume driver classes to reduce duplication"
Make scheduler modules pass conductor to add_instance_fault

The add_instance_fault_from_exc() method was recently changed to
take a conductor to avoid direct database access. The scheduler was
not updated for this, and thus was not passing it in a couple of
cases.

This makes those calls pass a conductor LocalAPI, resulting in direct
database access (which is desired from the scheduler). The tests that
one might have thought would catch this didn't because they mock out
the method itself. This fixes those and adds two tests that exercise
the add_instance_fault path all the way down to the DB API, which
would have caught it in the first place.

Fixes bug 1110808

Change-Id: If1c2988487d408a39fdf4080541f58f6bdac216c
Merge "Use install_venv_common.py from oslo."
Merge "Make scheduler modules pass conductor to add_instance_fault"