Add uuid and name slots to Disk/NIC ConfigObjects

This patch adds "uuid" and "name" slots to Disk and NIC ConfigObjects.

Signed-off-by: Christos Stavrakakis <cstavr@grnet.gr>
Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
Reviewed-by: Helga Velroyen <helgav@google.com>