Save connection info in libvirt after volume connect

The libvirt driver will connect volumes for BFV while processing
the guest configuration, but not save the connection_info into
the database. This adds a save there to make sure that any
storage driver details get persisted.

Related-bug: #1328245

Change-Id: Idd6ef94ba2129b65e685a0435bc79f213d6f3f04
Merge "Save connection info in libvirt after volume connect" into stable/havana