Add support to propagate ONOS log to Kafka with KafkaAppender in log4j2

- new OSGi Bundle to define extra imports for log4j2
- update OSGiWrapper to support fragment-host tag + bugfix
- add kafka-clients to onos-dependencies package
- add example of how to propagate log to Kafka via KafkaAppender
- bugfix to org.ops4j.pax.logging.cfg

Change-Id: I89992936101a48c6452082bf23c7133c20aa0b48
diff --git a/tools/package/dependencies/BUILD b/tools/package/dependencies/BUILD
index 63adf9c..bb50031 100644
--- a/tools/package/dependencies/BUILD
+++ b/tools/package/dependencies/BUILD
@@ -28,6 +28,7 @@
     "@org_apache_karaf_shell_console//jar",
     "@org_osgi_cmpn//jar",
     "@jersey_container_servlet//jar",
+    "@kafka_clients//jar",
 ]
 
 # Listed in the <dependencies> section with scope 'provided'