Added support for sort column

[kasemsun-su]

Add support for sort column like this
dataTable.columns(3).search( keyword ).draw();

code on nodejs back-end will be like this

Order.dataTables({
    limit: req.body.length,
    skip: req.body.start,
    search: {
        value: req.body.search.value,
        fields: ["order_no", "store_name", "vehicle_code"]
    },
    columns: [{
        value: req.body.columns[3].search.value,
        fields: ["zone"]
    }],
    sort: sortColumn(req.body,["order_no","order_date","zone","store_name","total_amount","vehicle_code","order_status"])
}).then(function (table) {
    .....
})