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.

Change-Id: Ia99e04ad80a2823a6852debf0919e72b2f93bd26
Related-bug: #1328245
Merge "Save connection info in libvirt after volume connect"