1. ubuntu: enable placement API in Nova
Until now, we were only deploying Placement API on Ubuntu because
packaging was too old. Though it's becoming a requirement in Ocata RC1
so before our CI breaks when Ubuntu will update their packages, let's
enable it now.
2. ubuntu: enable ::nova::cell_v2::simple_setup
Because we have to.
Change-Id: Id0ef365539a907c131167d745f9ac6eb1cd676fd