minor clean up in remote helper

-- remove unused method
-- don't repeat remote calls
-- split commands

Change-Id: Id23f34c41ba09bf2ef7622706459a03a4780a148
Reviewed-on: http://review.couchbase.org/36771
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Li Yang <lichenyang2@gmail.com>