CORD-535 Added purge and sync states CLIs

And improved result format of the existing CLIs

Change-Id: I49476ab52f77f6fadddf00dfc113c51153b300ed
diff --git a/src/main/java/org/opencord/cordvtn/api/net/VtnPort.java b/src/main/java/org/opencord/cordvtn/api/net/VtnPort.java
index 0ec1078..3ba4192 100644
--- a/src/main/java/org/opencord/cordvtn/api/net/VtnPort.java
+++ b/src/main/java/org/opencord/cordvtn/api/net/VtnPort.java
@@ -23,6 +23,7 @@
 import org.onlab.packet.VlanId;
 import org.openstack4j.model.network.Port;
 
+import java.util.Comparator;
 import java.util.Objects;
 import java.util.Set;
 
@@ -38,7 +39,7 @@
  */
 public final class VtnPort extends ServicePort {
 
-    private static final String ERR_IP_MISSING = "VTN port IP adderess is missing";
+    private static final String ERR_IP_MISSING = "VTN port IP address is missing";
 
     private final NetworkId netId;
     private final MacAddress mac;
@@ -56,6 +57,9 @@
         this.ip = ip;
     }
 
+    public static final Comparator<VtnPort> VTN_PORT_COMPARATOR =
+            (port1, port2) -> port1.netId().id().compareTo(port2.netId().id());
+
     /**
      * Returns the network ID of this port.
      *