MB-100: fix call _create_buckets in xdcr

Change-Id: I01e262771c91bc593f27eafd1b76051b4e330fe0
Reviewed-on: http://review.couchbase.org/24812
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>