Reorg kafka imports
Reorg kafka imports

  - kafka.KafkaClient is new async client
  - kafka.SimpleClient is old sync client
  - update copyright / author info
  - add BrokerConnection; drop KafkaConnection

scrapinghub/kafka-python,dpkp/kafka-python,scrapinghub/kafka-python,Yelp/kafka-python,mumrah/kafka-python,wikimedia/operations-debs-python-kafka,Aloomaio/kafka-python,wikimedia/operations-debs-python-kafka,ohmu/kafka-python,zackdever/kafka-python,Aloomaio/kafka-python,mumrah/kafka-python,Yelp/kafka-python,gamechanger/kafka-python,gamechanger/kafka-python,zackdever/kafka-python,dpkp/kafka-python,DataDog/kafka-python,ohmu/kafka-python