remove zero length field name in format string, to work in Python 2.6
Exception hierarchy, invalidate more md on errors
Merge pull request #99 from vadimg/master

remove zero length field name in format string, to work in Python 2.6
Throw KafkaUnavailableError when no brokers available
Add a few 9s test_multi_process_consumer, make clear what setUp is doing
Make integration test warming more intuitive
Merge pull request #100 from cosbynator/no_infinite_loops_real

Branch fix: No infinite loops during metadata requests, invalidate metadata more, exception hierarchy
Implement offset fetch/commit via zookeeper.

* Tried to be consistent with the Scala client.
* Support in MultiProcessConsumer not implemented.
* Removed check for self.count_since_commit in commit() since we may have manually changed the offsets (e.g. with a seek)
resolve merge conflicts