MB-12726: add mode option for incremental backup
MB-12726: add mode option for incremental backup

Change-Id: Ibacd9d33a2e118473d9dea6e395cb48e87553632
Reviewed-on: http://review.couchbase.org/43433
Reviewed-by: Bin Cui <ed18693fff32c00e22495f4877a3b901bed09041@gmail.com>
Tested-by: Bin Cui <ed18693fff32c00e22495f4877a3b901bed09041@gmail.com>

couchbase/couchbase-cli,couchbase/couchbase-cli