Starting to include kafka-integration app as part of Buck build.

- refactored to follow the api & app structure
- added buck files
- builds and loads
- cleaned-up and fixed number of pom files to function as expected
      (meaning "mvn clean install" actually works)

Change-Id: Ib896269c4986f6ee5cd6bae7cf508f71b64f59f9
diff --git a/apps/kafka-integration/api/src/main/java/org/onosproject/kafkaintegration/api/EventSubscriptionService.java b/apps/kafka-integration/api/src/main/java/org/onosproject/kafkaintegration/api/EventSubscriptionService.java
index 1f08b55..b725f0f 100644
--- a/apps/kafka-integration/api/src/main/java/org/onosproject/kafkaintegration/api/EventSubscriptionService.java
+++ b/apps/kafka-integration/api/src/main/java/org/onosproject/kafkaintegration/api/EventSubscriptionService.java
@@ -50,8 +50,8 @@
      * Allows registered listener to subscribe for a specific event type.
      *
      * @param subscriber Subscription data containing the event type
-     * @throws InvalidGroupIdException
-     * @throws InvalidApplicationException
+     * @throws InvalidGroupIdException if the subscriber group is duplicate
+     * @throws InvalidApplicationException if the application has not been registered
      */
     void subscribe(EventSubscriber subscriber)
             throws InvalidGroupIdException, InvalidApplicationException;
@@ -60,8 +60,8 @@
      * Allows the registered listener to unsubscribe for a specific event.
      *
      * @param subscriber Subscription data containing the event type
-     * @throws InvalidGroupIdException
-     * @throws InvalidApplicationException
+     * @throws InvalidGroupIdException if the subscriber group does not exist
+     * @throws InvalidApplicationException if the application has not been registered
      */
     void unsubscribe(EventSubscriber subscriber)
             throws InvalidGroupIdException, InvalidApplicationException;