[ONOS-3642] Add GUI Meter View

This implements the web GUI meter view.
Current implementation uses the group table icon for meter,
and the revised meter icon will be updated in following commit.
See ONOS-3645 for detail.

Change-Id: Iaa2e673ef83024135d757a2aaec1c31a87263217
diff --git a/web/gui/src/main/java/org/onosproject/ui/impl/UiExtensionManager.java b/web/gui/src/main/java/org/onosproject/ui/impl/UiExtensionManager.java
index 86cf038..c29ebe1 100644
--- a/web/gui/src/main/java/org/onosproject/ui/impl/UiExtensionManager.java
+++ b/web/gui/src/main/java/org/onosproject/ui/impl/UiExtensionManager.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2015 Open Networking Laboratory
+ * Copyright 2015,2016 Open Networking Laboratory
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -83,6 +83,7 @@
                 new UiViewHidden("flow"),
                 new UiViewHidden("port"),
                 new UiViewHidden("group"),
+                new UiViewHidden("meter"),
                 new UiView(NETWORK, "link", "Links", "nav_links"),
                 new UiView(NETWORK, "host", "Hosts", "nav_hosts"),
                 new UiView(NETWORK, "intent", "Intents", "nav_intents"),
@@ -99,6 +100,7 @@
                         new FlowViewMessageHandler(),
                         new PortViewMessageHandler(),
                         new GroupViewMessageHandler(),
+                        new MeterViewMessageHandler(),
                         new IntentViewMessageHandler(),
                         new ApplicationViewMessageHandler(),
                         new SettingsViewMessageHandler(),