Miscellaneous updates to inventory interfaces

- Placed interfaces corresponding to physical items under
  Inventory/Item/ and interfaces which serve as item decorators under
  Inventory/Decorator/.
- Add some new dbus interfaces.
- Restructured Board item related interfaces such that there's a parent
  Board interface, and derivatives such as Motherboard, IO board, etc.
- Added new properties to existing interfaces.

Change-Id: I52b7c1a789df6745d1786d927fab06db40524448
Signed-off-by: Deepak Kodihalli <dkodihal@in.ibm.com>
diff --git a/xyz/openbmc_project/Inventory/Item.interface.yaml b/xyz/openbmc_project/Inventory/Item.interface.yaml
index dfae631..82e4c75 100644
--- a/xyz/openbmc_project/Inventory/Item.interface.yaml
+++ b/xyz/openbmc_project/Inventory/Item.interface.yaml
@@ -3,11 +3,11 @@
     within the inventory namespace.
 properties:
     - name: PrettyName
-      type: s
+      type: string
       description: >
           The human readable name of the item.
     - name: Present
-      type: b
+      type: boolean
       description: >
           Whether or not the item is present.