Create the nova_api_cell0 database
Create the nova_api_cell0 database

As part of Nova cellsv2 there is now a third database that must be setup
for use by Nova. This database is an exact copy of the 'nova' database.
Only do this if NOVA_CONFIGURE_CELLSV2 is overridden.

Change-Id: I8775b8066ba85fbdbcdfb42c28cb567fc7759fe5

noironetworks/devstack,richliu/devstack,openstack-dev/devstack,nawawi/openstack,bswartz/devstack,group-policy/devstack,bswartz/devstack,group-policy/devstack,nawawi/openstack,dtroyer/devstack,richliu/devstack,dtroyer/devstack,noironetworks/devstack,openstack-dev/devstack