Apache Kafka integration components for SAMOA

As of now Apache SAMOA includes no integration components for Apache Kafka, meaning in particular no possibility to read data coming from Kafka and write data with prediction results back to Kafka.
The key assumptions for the development of Kafka-related components are as follows:
1) develop support for input data stream arriving to Apache Samoa via Apache Kafka
2) develop support for output data stream produced by Apache Samoa, including the results of stream mining and forwarded to Apache Kafka to be provided in this way to other modules consuming the stream.
This makes the goal of this issue is to create the following components:
1) KafkaEntranceProcessor in samoa-api. This entrance processor will be able to accept incoming Kafka stream. It will require KafkaDeserializer interface implementation to be delivered. The role of Deserializer would be to translate incoming Apache Kafka messages into implementation of Instance interface of SAMOA.
2) KafkaDestinationProcessor in samoa-api. Similarly to the KafkaEntranceProcessor, this processor would require KafkaSerializer interface implementation to be delivered. The role of Serializer would be to create a Kafka message from the underlying Instance class.
3) KafkaStream, as the extension to existing streams (e.g. InstanceStream), would take similar role to other streams, and will provide the control over Instances flows in the entire topology.

Moreover, the following assumptions are considered:
1) Components would be implemented with the use of most up-to-date version of Apache Kafka, i.e. 0.10
2) Samples of aforementioned Serializer and Deserializer would be delivered, both supporting AVRO and JSON serialization of Instance objects.
3) Sample testing classes providing reference use of Kafka source and destination would be included in the project as well.