Update to use flavor_extra_specs.
Update to use flavor_extra_specs.

Nova recently dropped the deprecated instance_type_extra_specs
config option. This commit updates our TripleO nova.conf
config to use the new format.

Closes-bug #1330735

Change-Id: I4b35b98be789d689a95c363790ff2bdd548eae10

openstack/tripleo-image-elements,rdo-management/tripleo-image-elements,rdo-management/tripleo-image-elements,radez/tripleo-image-elements,openstack/tripleo-image-elements,radez/tripleo-image-elements