Upr protocol change to improve rollbacks during a failover case

There is a case where a client may have a partial snapshot during a failover and end up missing items. As a result we need to modify our stream request message and also add a start snapshot message.

Stream request (Remove high seqno, add last full snapshot seqno and next snapshot seqno)
Start snapshot should contain the end seqno for the current snapshot. We should also add a flags field which can indicate whether or not this snapshot is a disk or memory snapshot.