ONOS-3321 Added ability for applications to register a deactivation hook.

Change-Id: Ic67e8066320e9997fdbe5b74beb17450371d0e00
diff --git a/oneping/src/main/java/org/onos/oneping/OnePing.java b/oneping/src/main/java/org/onos/oneping/OnePing.java
index 58d2eb4..038921a 100644
--- a/oneping/src/main/java/org/onos/oneping/OnePing.java
+++ b/oneping/src/main/java/org/onos/oneping/OnePing.java
@@ -103,7 +103,8 @@
 
     @Activate
     public void activate() {
-        appId = coreService.registerApplication("org.onos.oneping");
+        appId = coreService.registerApplication("org.onosproject.oneping",
+                                                () -> log.info("Periscope down."));
         packetService.addProcessor(packetProcessor, PRIORITY);
         flowRuleService.addListener(flowListener);
         packetService.requestPackets(intercept, PacketPriority.REACTIVE, appId);