Expose VPNaaS settings

The current version of puppet_openstack_builder exposes Neutron's
LBaaS and FWaaS services, but doesn't expose VPNaaS.  This patch
adds data mappings and settings in user.common.yaml that allow
users to set up VPNaaS.

Change-Id: Ic6f396e09c4b7fff1285cbcc304bb3f56d7137ef
Implements: blueprint enable-vpnaas
Merge "Expose VPNaaS settings"