MB-100: update name of reb_mode parameter

Change-Id: Ic91b6771a39e8e2e3014b2c7c9bda8c002162336
Reviewed-on: http://review.couchbase.org/24659
Reviewed-by: Pavel Paulau <pavel.paulau@gmail.com>
Tested-by: Pavel Paulau <pavel.paulau@gmail.com>