Refresh Method for Programmatic update of Fields after Initialization

I came across an issue when re-using datepair start/end fields. The timeDelta and dateDelta would be out of sync with the new data since the initial timeDelta and dateDelta are only set when first calling .datepicker().

I updated datepair.js to include a method called refresh that simply resets the timeDelta and dateDelta to reflect the values in the date and time fields.