Add CLI command to view provisioned subscribers

Change-Id: I67a49d7fa569e9f4f28eb8eaea1b34ba2bd5a5fa
diff --git a/app/src/main/java/org/onosproject/olt/impl/Olt.java b/app/src/main/java/org/onosproject/olt/impl/Olt.java
index 976fcaa..a62b115 100644
--- a/app/src/main/java/org/onosproject/olt/impl/Olt.java
+++ b/app/src/main/java/org/onosproject/olt/impl/Olt.java
@@ -67,6 +67,7 @@
 import org.osgi.service.component.ComponentContext;
 import org.slf4j.Logger;
 
+import java.util.Collection;
 import java.util.Dictionary;
 import java.util.List;
 import java.util.Map;
@@ -243,6 +244,11 @@
     }
 
     @Override
+    public Collection<Map.Entry<ConnectPoint, VlanId>> getSubscribers() {
+        return subscribers.entrySet();
+    }
+
+    @Override
     public Map<DeviceId, AccessDeviceData> fetchOlts() {
         return Maps.newHashMap(oltData);
     }
@@ -459,11 +465,10 @@
         public void event(DeviceEvent event) {
             DeviceId devId = event.subject().id();
             if (!oltData.containsKey(devId)) {
-                log.debug("Device {} is not an OLT", devId);
                 return;
             }
             switch (event.type()) {
-                //TODO: Port handling and bookkeeping should be inproved once
+                //TODO: Port handling and bookkeeping should be improved once
                 // olt firmware handles correct behaviour.
                 case PORT_ADDED:
                     if (!oltData.get(devId).uplink().equals(event.port().number()) &&