Work toward ONOS-1451: Separate Event Key space per instance

Misc changes and cleanup:
* Added new class OnosInstanceId
* Replace (as appropriate) the string controllerId (and associated methods)
  with the new class OnosInstanceId
* Renaming: Host -> Device
  - Method getDeviceID -> getHostID
  - Changed Host Key ID prefix 'D' to 'H'
  - Few renaming of Host -> Device inside Javadoc

Change-Id: I59c20d68277ecde2f7df4e7097a4a52d5786df1b
diff --git a/src/test/java/net/onrc/onos/core/registry/ZookeeperRegistryTest.java b/src/test/java/net/onrc/onos/core/registry/ZookeeperRegistryTest.java
index ca56736..5490162 100644
--- a/src/test/java/net/onrc/onos/core/registry/ZookeeperRegistryTest.java
+++ b/src/test/java/net/onrc/onos/core/registry/ZookeeperRegistryTest.java
@@ -9,6 +9,7 @@
 import net.floodlightcontroller.test.FloodlightTestCase;
 import net.onrc.onos.core.registry.StandaloneRegistryTest.LoggingCallback;
 import net.onrc.onos.core.registry.ZookeeperRegistry.SwitchLeaderListener;
+import net.onrc.onos.core.util.OnosInstanceId;
 
 import org.apache.curator.RetryPolicy;
 import org.apache.curator.framework.CuratorFramework;
@@ -115,25 +116,26 @@
     }
 
     /**
-     * Test if {@link ZookeeperRegistry#getControllerId()} correctly returns registered ID.
+     * Test if {@link ZookeeperRegistry#getOnosInstanceId()} correctly returns
+     * registered ID.
      *
      * @throws Exception
      */
     @Test
-    public void testGetControllerId() throws Exception {
+    public void testGetOnosInstanceId() throws Exception {
         String controllerIdToRegister = "controller1";
 
         // try before controller is registered
-        String controllerId = registry.getControllerId();
-        assertNull(controllerId);
+        OnosInstanceId onosInstanceId = registry.getOnosInstanceId();
+        assertNull(onosInstanceId);
 
         // register
         registry.registerController(controllerIdToRegister);
 
-        // call getControllerId and verify
-        controllerId = registry.getControllerId();
-        assertNotNull(controllerId);
-        assertEquals(controllerIdToRegister, controllerId);
+        // call getOnosInstanceId and verify
+        onosInstanceId = registry.getOnosInstanceId();
+        assertNotNull(onosInstanceId);
+        assertEquals(controllerIdToRegister, onosInstanceId.toString());
     }
 
     /**