NCBC-239: RestSharpHttpClient timeout set to incorrect timespan property

Change-Id: I027dc83aa43ed6d5a43f86246adc653c2c78ce64
Reviewed-on: http://review.couchbase.org/25311
Tested-by: Saakshi Manocha <saakshi.manocha@globallogic.com>
Reviewed-by: Saakshi Manocha <saakshi.manocha@globallogic.com>