CBSE-1543: fix setting-alert port option

Change-Id: Ib2fd0afdb9ac4069f9323d3367bd14d794c580fc
Reviewed-on: http://review.couchbase.org/43954
Reviewed-by: Bin Cui <bin.cui@gmail.com>
Tested-by: Bin Cui <bin.cui@gmail.com>