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/Decorator/Cacheable.interface.yaml b/xyz/openbmc_project/Inventory/Decorator/Cacheable.interface.yaml
new file mode 100644
index 0000000..2809de0
--- /dev/null
+++ b/xyz/openbmc_project/Inventory/Decorator/Cacheable.interface.yaml
@@ -0,0 +1,10 @@
+description: >
+    Implement to indicate item availability changes.
+properties:
+    - name: Cached
+      type: boolean
+      description: >
+          Whether or not the item is cached.  When true, the item
+          and its remaining attributes are undefined.
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4