Initial sketch of the virtual network constructs.

Change-Id: Ibcdafb9e56edb29fb37b80d7b0da321ad989c564
diff --git a/core/api/src/main/java/org/onosproject/net/Device.java b/core/api/src/main/java/org/onosproject/net/Device.java
index e36d762..8066a7a 100644
--- a/core/api/src/main/java/org/onosproject/net/Device.java
+++ b/core/api/src/main/java/org/onosproject/net/Device.java
@@ -26,7 +26,7 @@
      * Coarse classification of the type of the infrastructure device.
      */
     public enum Type {
-        SWITCH, ROUTER, ROADM, OTN, ROADM_OTN, FIREWALL, BALANCER, IPS, IDS, CONTROLLER, OTHER
+        SWITCH, ROUTER, ROADM, OTN, ROADM_OTN, FIREWALL, BALANCER, IPS, IDS, CONTROLLER, VIRTUAL, OTHER
     }
 
     /**
@@ -79,10 +79,4 @@
      */
     ChassisId chassisId();
 
-    // Device realizedBy(); ?
-
-    // ports are not provided directly, but rather via DeviceService.getPorts(Device device);
-
-    // Set<Behavior> behaviours(); // set of supported behaviours
-
 }