INTEXT-44 - Add Kafka Support

* Add Inbound adapter
* Add Outbound adapter
* Add serialization
* Initial Documentation
* Add unit tests
* Add async producer
* Support Kafka 0.8
* Add Kafka Sample

See: https://jira.springsource.org/browse/INTEXT-44
INTEXT-44 - Polishing

* Upgrade to Gradle 1.6
* Upgrade Sonar plugin to SonarRunner
* Upgrade a few dependencies (e.g. JUnit, Spring Integration)
* Remove deprecations (e.g. JUnit)
* Convert spaces to tabs
* Add author tags
* Add @since
Merge pull request #42 from sobychacko/INTEXT-44

* sobychacko-INTEXT-44:
  INTEXT-44 - Polishing
  INTEXT-44 - Add Kafka Support