Add availability decorator interface

In redfish objects are allowed to be marked as
unavailable and currently we have no way of determining
that something is offline. Implement an interface that
can be used to mark something as offline.

Change-Id: Ib27efb22426f70e1437884e8f8de131a5e968dcd
Signed-off-by: James Feist <james.feist@linux.intel.com>
diff --git a/xyz/openbmc_project/State/Decorator/Availability.interface.yaml b/xyz/openbmc_project/State/Decorator/Availability.interface.yaml
new file mode 100644
index 0000000..2db2c17
--- /dev/null
+++ b/xyz/openbmc_project/State/Decorator/Availability.interface.yaml
@@ -0,0 +1,8 @@
+description: >
+    Implement to indicate the availablity status of the object
+properties:
+    - name: Available
+      type: boolean
+      description: >
+        True if the object can be accessed.
+      default: true