just fixing a silly except formatting mistake
Merge pull request #216 from zever/nit-incorrect-except-format

Fix except clause error in test_failover_integration
Improve metadata protocol handling
  - add MetadataRequest and MetadataResponse namedtuples
  - add TopicMetadata namedtuple
  - add error codes to Topic and Partition Metadata
  - add KafkaClient.send_metadata_request() method
  - KafkaProtocol.decode_metadata_response changed
    to return a MetadataResponse object
    so that it is consistent with server api: [broker_list, topic_list]
Rearrange KafkaClient method order to group client metadata methods together
if error code is not recognized in check_error: raise UnknownError
No more custom LeaderUnavailableError exception -- raise LeaderNotAvailableError
Refactor internal metadata dicts in KafkaClient
 - use helper methods not direct access
 - add get_partition_ids_for_topic
 - check for topic and partition errors during load_metadata_for_topics
 - raise LeaderNotAvailableError when topic is being auto-created
   or UnknownTopicOrPartitionError if auto-creation off
Dont need to use callbacks for offset fetch requests
load_metadata_for_topics should raise exceptions on explicit topic args
Raise UnknownTopicOrPartitionError immediately in ensure_topic_exists -- server is not auto-creating
Use standard exceptions in client._get_leader_for_partition()
- drop custom PartitionUnavailable exception
- raise UnknownTopicOrPartitionError or LeaderNotAvailableError
- add tests for exception raises
Add test for sending produce request to unknown topic w/o auto-creation
Add client unit tests for has_metadata_for_topic and ensure_topic_exists