For our line chart it would help a lot to be able to display the date (category) along with the value when the user hovers over with the mouse.

If dataItem was added to ChartSeriesTooltipTemplate then that would allow full flexibility, which would be nice.

http://www.telerik.com/kendo-angular-ui/components/charts/api/TooltipComponent/#toc-format

http://www.telerik.com/kendo-angular-ui/components/charts/api/SeriesTooltipTemplateDirective/