Change to update node properties

- inventoryServiceShim to trigger node description update
- Inventory Service to accept node properties updates for known nodes only
- Inventory Service to publish only effective node properties update and on default container only
- Minor changes to the Property classes toString() methods
- Removed toString() overridden method in UpdateType as default toString() which prints the enum name is self explicative and serves better in logs
Signed-off-by: Alessandro Boch <aboch@cisco.com>