Updates to work with the latest kafka-python API changes

tail2kafka would not work with the latest kafka-python library.  It seems that the API for both the KafkaClient and the SimpleProducer have changed.  The KafkaClient now wants the host/port as a single string like "localhost:9092".  The SimpleProducer no longer wants the topic.  I also imported the logging because it made it easier to use the logging in the kafka-python library when debugging and errors arise.