Added endPortA/B to UiLink class.
Removed 'online' property from UiDevice, choosing to look up availability on the fly from device service.

Change-Id: Ib14ab371a11c442a30cf407f11d366271d087c68
diff --git a/core/api/src/main/java/org/onosproject/ui/model/topo/UiRegionDeviceLink.java b/core/api/src/main/java/org/onosproject/ui/model/topo/UiRegionDeviceLink.java
index f749473..e907fbc 100644
--- a/core/api/src/main/java/org/onosproject/ui/model/topo/UiRegionDeviceLink.java
+++ b/core/api/src/main/java/org/onosproject/ui/model/topo/UiRegionDeviceLink.java
@@ -63,6 +63,13 @@
         return device + UiLinkId.ID_PORT_DELIMITER + port;
     }
 
+    // no port for end-point A
+
+    @Override
+    public String endPortB() {
+        return port.toString();
+    }
+
     /**
      * Returns the identity of the region.
      *