Add the snapshot start/end squence numbers to the OpenStream API
Add the snapshot start/end squence numbers to the OpenStream API

These are needed in order to allow clients to resume from partial
snapshots.

Change-Id: I0fd8648df4cd60530d5ca2407b68df58cc3850f1
Reviewed-on: http://review.couchbase.org/56461
Reviewed-by: Brett Lawson <c8c4369773d7d7226e031f0c4af62e3f38a08510@gmail.com>
Tested-by: Brett Lawson <c8c4369773d7d7226e031f0c4af62e3f38a08510@gmail.com>

brett19/gocb