Consumer enhancements and coordinator bugfix.

• Add a check to wait topic autocreation in Consumer, instead of raising UnknownTopicOrPartitionError (PR #92 by fabregas)
• Consumer now stops consumption after consumer.stop() call. Any new get* calls will result in ConsumerStoppedError (PR #81)
• Added exclude_internal_topics option for Consumer (PR #111)
• Better support for pattern subscription when used with group_id (part of PR #111)
• Fix for Consumer subscribe and JoinGroup race condition (issue #88). Coordinator will now notice subscription changes during rebalance and will join group again. (PR #106)
• Changed logging messages according to KAFKA-3318. Now INFO level should be less messy and more informative. (PR #110)
• Add support for connections_max_idle_ms config (PR #113)