add support for neutron/nova notifications

This adds options to configure the Neutron -> Nova notifications of port
status and data changes.  Requires a recent puppet-neutron module with
neutron::server::notifications manifest (e.g.,
https://review.openstack.org/#/c/88410/)

Change-Id: I26684a8fe5df79db6b68a5bd733619517376660c
Closes-bug: 1306337
support ssh-based live migration

This change introduces support for ssh key generation and distribution
to support instance migration via qemu+ssh connections to remote
hypervisors.

This change requires https://review.openstack.org/#/c/89620/ (which
introduces support for ssh keys into puppet-nova)

Change-Id: I38c2aee3a7415bb69a099419f6149151c7d6b52c