Enforce MAX BYTES for transferring batch records

[sehz]

Fluvio uses zero copy I/o to transfer records from SPU to client.
Records to need to be limit since maximum bytes can be up to 1G for each segment.

Solution:

• SPU: Limit transferring file slice. This will create potentially truncated last batch
• Kf decoder: When decoding DefaultRecords, ignore any batch that can't be decoded
• Client: Use offset in the last batch to retrieve next batches for streaming cases
• SPU-SPU: Apply spu-message-size to limit bytes

[sehz]

Everything except item 3 is implemented. That will be done as part of Issue #72 (new client API)