Add OffsetFetchRequest protocol. Some small changes in tests.
Fix correctly dispose gzip tests
Merge PR #16 with modifications to conventions

Pull in the added OffsetFetchRequest class and modified it to match the
style convention of the other classes.
Update OffsetCommitRequest to match the new wire protocol as of 0.8.1.1
Commit/Fetch not completely implemented yet.  Protocol requires new
request ( ConsumerMetadataRequest)