Defining notion of a projectable entity.

Opened up DefaultDriverHandler to accept arbitrary DriverData.

Added clarifying documentation to DriverData.

Change-Id: Ic96251703bf0461caef4f3950658e2073d889653
diff --git a/core/api/src/main/java/org/onosproject/net/driver/DefaultDriverHandler.java b/core/api/src/main/java/org/onosproject/net/driver/DefaultDriverHandler.java
index 28fdb2f..e415e9a 100644
--- a/core/api/src/main/java/org/onosproject/net/driver/DefaultDriverHandler.java
+++ b/core/api/src/main/java/org/onosproject/net/driver/DefaultDriverHandler.java
@@ -25,7 +25,7 @@
  */
 public class DefaultDriverHandler implements DriverHandler {
 
-    private final DefaultDriverData data;
+    private final DriverData data;
 
     // Reference to service directory to provide run-time context.
     protected static ServiceDirectory serviceDirectory = new DefaultServiceDirectory();
@@ -35,7 +35,7 @@
      *
      * @param data driver data to attach
      */
-    public DefaultDriverHandler(DefaultDriverData data) {
+    public DefaultDriverHandler(DriverData data) {
         this.data = data;
     }