A simpler kafka consumer

```
kafka = KafkaConsumer('topic1')
for m in kafka:
    print m

kafka = KafkaConsumer('topic1', 'topic2',
                      group_id='my_consumer_group',
                      auto_commit_enable=True,
                      auto_commit_interval_ms=30 * 1000,
                      auto_offset_reset='smallest')

for m in kafka:
    process_message(m)
    kafka.task_done(m)
```
I tried to do """default={key_name}""".format(**DEFAULT_CONSUMER_CONFIG) , but when i try to examine from shell via `help(KafkaConsumer)` i see empty docstring...  does this work for you?  testing generically via python shell also doesn't work.  have you gotten something like this to work before?