[sheepdog] compatibility of dog command between new and old cluster

[Liu Yuan]

On Fri, Jul 18, 2014 at 10:35:46AM +0800, Ruoyu wrote:
> Hi there,
> 
> Should we upgrade SD_PROTO_VER to 0x03 to avoid it because vdi
> object size is different since ledger object is introduced?

should increment SD_SHEEP_PROTO_VER for dog and sheep communcation

Thanks
Yuan