MB-11414: Producer's state before active stream tasks

- Ensure producer's state is indeed BACKFILLING before
activestream's markDiskSnapshot task.

Change-Id: Ib68bb39100db06d8435997b327ed15439601b03a
Reviewed-on: http://review.couchbase.org/38185
Reviewed-by: Michael Wiederhold <mike@couchbase.com>
Tested-by: abhinav dangeti <abhinav@couchbase.com>
Add stat to PassiveStream class for last received seqno

Change-Id: I88f0756f6857a9762c6bdbc46884d9dee4af567a
Reviewed-on: http://review.couchbase.org/38201
Reviewed-by: abhinav dangeti <abhinav@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>
Use backfill phase to determine if a stream can be created

Change-Id: I9dd836d7de7bb311aecf4fbe607765409181ae62
Use the real persistence number

Change-Id: Ifb260aeed3b05776f6fc3d73bae20168d3ffcbbe
Make sure we update the last persited seqno properly

Change-Id: Ie975dae49d5271f31ba7ee48fdb9e06e30eeb8ae
Fix off by one error

Change-Id: I3de5c8244f68fbb764f856877a04c2f29fb1f4be