python -m cli interfaces for kafka.admin, kafka.consumer, kafka.producer

[dpkp]

Builds on @rdiomar's work in #119 :

$ python -m kafka.producer -b 127.0.0.1:9092 -t "hello"
yo dude
what's up?

# Meanwhile, in another terminal...
$ python -m kafka.consumer -b 127.0.0.1:9092 -t "hello" -g "analytics"
yo dude
what's up?

Adding kafka.admin to the mix:

$ python -m kafka.admin -b 127.0.0.1:9092 cluster describe
{'brokers': [{'host': 'localhost', 'node_id': 0, 'port': 9092, 'rack': None}],
 'cluster_id': 'xxx-yyy',
 'controller_id': 0,
 'throttle_time_ms': 0}