Removed static DHCP mapping when a VM is vanished

Change-Id: I96aad216ebb061396bf0af9a733b14dbde20cdaa
diff --git a/src/main/java/org/onosproject/cordvtn/CordVtn.java b/src/main/java/org/onosproject/cordvtn/CordVtn.java
index 4c0bf72..bd8dad2 100644
--- a/src/main/java/org/onosproject/cordvtn/CordVtn.java
+++ b/src/main/java/org/onosproject/cordvtn/CordVtn.java
@@ -482,6 +482,7 @@
                  host.ipAddresses().stream().findFirst().get());
 
         ruleInstaller.removeBasicConnectionRules(host);
+        dhcpService.removeStaticMapping(host.mac());
 
         CordService service = getCordService(vNet);
         if (service == null) {