KafkaConsumer should not skip a corrupted record after throwing an exception.

In 0.10.2, when there is a corrupted record, KafkaConsumer.poll() will throw an exception and block on that corrupted record. In the latest trunk this behavior has changed to skip the corrupted record (which is the old consumer behavior). With KIP-98, skipping corrupted messages would be a little dangerous as the message could be a control message for a transaction. We should fix the issue to let the KafkaConsumer block on the corrupted messages.