kafka-1549; dead brokers coming in the TopicMetadataResponse; patched by Nicu Marasoiu; reviewed by Jun Rao
kafka-1542; normal IOException in the new producer is logged as ERROR; patched by David Corley; reviewed by Jun Rao
kafka-1414; Speedup broker startup after hard reset; patched by Anton Karamanov; reviewed by Jay Kreps and Jun Rao