Fix VPLS app

Remove listeners from HostService and InterfaceService after VPLS
deactivate.

Change-Id: I9d16a3e44fe7500e26f662f1d743315167dd890b
diff --git a/apps/vpls/src/main/java/org/onosproject/vpls/Vpls.java b/apps/vpls/src/main/java/org/onosproject/vpls/Vpls.java
index bd9bf0e..658ddad 100644
--- a/apps/vpls/src/main/java/org/onosproject/vpls/Vpls.java
+++ b/apps/vpls/src/main/java/org/onosproject/vpls/Vpls.java
@@ -140,6 +140,8 @@
 
     @Deactivate
     public void deactivate() {
+        hostService.removeListener(hostListener);
+        interfaceService.removeListener(interfaceListener);
         configService.removeListener(configListener);
         intentSynchronizer.removeIntentsByAppId(appId);
         log.info("Deactivated");