Sort columns within widgets.

The widget creation defines the sort order of the columns but for quick changes, it would be very helpful to be able to double-click a column header and have it sort, just like we do in vCenter.  Click the column again and it will reverse the order (ascending to descending, etc.).  When I see a table like VM latency, it would be helpful to click on the header of the highest latency and try to identify the worst offendors so I can see if it's one with read latency or write latency without editing the widget.