Set nova's default_floating_pool setting.
Set nova's default_floating_pool setting.

Without this the floating-ip extension looks for a neutron network
called 'nova' to handle floating IP requests.

Change-Id: If04bb47b2d2df4e87d0dd724c4598b94f5c97872
Fixes-Bug: #1239450

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