INTEXT-110: Update Kafka version to 0.8.1.1

JIRA: https://jira.spring.io/browse/INTEXT-110

Perform the necessary API Changes (Partioner interface in Kafka is now non-genericized for Keys - concrete Object is the new type for Key)
Unit test updates for an internal Kafka class (MessageMetadata)
Updates for the samples Kafka project to use the new M2 snapshot, Spring 4.0 Messaging changes, other build related minor changes, etc.