use private val, add logs and license headers
connect gearpump with Kafka

Conflicts:
	build.sbt
use private val, add logs and license headers
add emit batch size and KafkaBolt
rebased after pulling in PR#60
add back design diagram
update the image links
Merge pull request #61 from clockfly/master

update the document links
Merge branch 'kafka_spout' of https://github.com/manuzhang/gearpump into kafka_spout

Conflicts:
	build.sbt
	core/src/main/resources/shell.scala
Merge pull request #54 from manuzhang/kafka_spout

connect gearpump with Kafka
Merge remote-tracking branch 'remotes/upstream/master'

Conflicts:
	core/src/main/resources/shell.scala
	examples/src/main/scala/org/apache/gearpump/streaming/examples/kafka/KafkaSpout.scala