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/main/java/net/onrc/onos/core/topology/Host.java b/src/main/java/net/onrc/onos/core/topology/Host.java
index 71ede78..05849c5 100644
--- a/src/main/java/net/onrc/onos/core/topology/Host.java
+++ b/src/main/java/net/onrc/onos/core/topology/Host.java
@@ -16,27 +16,27 @@
 @JsonSerialize(using = HostSerializer.class)
 public interface Host extends ITopologyElement {
     /**
-     * Get the device MAC address.
+     * Gets the Host MAC address.
      *
-     * @return the device MAC address.
+     * @return the Host MAC address.
      */
     public MACAddress getMacAddress();
 
     /**
-     * Get the device attachment points.
+     * Gets the Host attachment points.
      * <p/>
      * TODO: There is only 1 attachment point right now.
      * TODO: Add requirement for Iteration order? Latest observed port first.
      *
-     * @return the device attachment points.
+     * @return the Host attachment points.
      */
     public Iterable<Port> getAttachmentPoints();
 
     /**
-     * Get the device last seen time.
+     * Gest the Host last seen time.
      * <p/>
      *
-     * @return the device last seen time. (UTC in ms)
+     * @return the Host last seen time. (UTC in ms)
      */
     public long getLastSeenTime();
 }