xenapi: apply firewall rules in finish_migrate

When security groups were added, the rules were not re-applied to
servers that have been migrated to a new hypervisor.

This change ensures the firewall rules are applied as part of creating
the new VM in finish_migrate. This code follows a very similar pattern
to the code in spawn, and that is where the cut and paste code comes
from. This code duplication was removed in Havana.

Fixes bug 1073306

Change-Id: I6295a782df328a759e358fb82b76dd3f7bd4b39e
Merge "xenapi: apply firewall rules in finish_migrate" into stable/grizzly