cyclades: Delete stale NICs before migration

Extend migration file to delete NICs that belong to VMs that have
already been deleted. Such NICs may exist due to a bug in previous versions
of Synnefo, and are totally useless. Also, they must be removed because
they will appear as stale ports in the new network API.

snf-cyclades-app/synnefo/db/migrations/0080_nics_to_ips.py

@@ -9,6 +9,8 @@ class Migration(DataMigration):
     def forwards(self, orm):
         "Write your forwards methods here."
         # Note: Remember to use orm['appname.ModelName'] rather than "from appname.models..."
+        # Delete stale NICs
+        orm.NetworkInterface.objects.filter(machine__deleted=True).delete()
         for nic in orm.NetworkInterface.objects.all():
             userid = nic.machine.userid
             nic.userid = userid