KAFKA-925 Add a partition key that overrides the message's stored key. Patch reviewed by Joel.
KAFKA-995 Ensure that replica fetch size is > max message size on server.
KAFKA-985 integer overflow in log time configuration values. Patch from Frank Fejes.
KAFKA-615 fsync asynchronous from log roll. Patch reviewed by Jun and Sriram.
KAFKA-1009 DumpLogSegments tool should return error on non-existing files; reviewed by Neha Narkhede