Cleaning up and enhancing driver subsystem and the flow objective subsystem.

Change-Id: Ica600ef1aaa46d19e764cd7a197454a4e0f85a08
diff --git a/core/api/src/main/java/org/onosproject/net/driver/DriverHandler.java b/core/api/src/main/java/org/onosproject/net/driver/DriverHandler.java
index 0fb46aa..6e8a354 100644
--- a/core/api/src/main/java/org/onosproject/net/driver/DriverHandler.java
+++ b/core/api/src/main/java/org/onosproject/net/driver/DriverHandler.java
@@ -21,6 +21,13 @@
 public interface DriverHandler {
 
     /**
+     * Returns the parent device driver.
+     *
+     * @return device driver
+     */
+    Driver driver();
+
+    /**
      * Returns the device driver data.
      *
      * @return device driver data