Specify cell0 db creation
Specify cell0 db creation

This change pulls the hard coded value out of puppet-tripleo to later
allow people to skip the cell0 creation if they want a more complex cell
v2 setup for nova.

Change-Id: I08119d781ef60750cc19753bc03190e413159925
Related-Bug: #1649341

dprince/tripleo-heat-templates,openstack/tripleo-heat-templates,openstack/tripleo-heat-templates,dprince/tripleo-heat-templates