Clicking on columns

There should be a way to add event handlers to columns, otherwise you have to wrap everything in a div that only exists for that purpose.
```elm
    Grid.column
         []
         [ div [ Html.Events.onClick Clicked ] whatYouReallyWantedToRender ] ]
```

I am thinking an api like

```elm
    Grid.column [] []
        |> Grid.onClick Clicked
        |> Grid.on "mouseup" MousedUp
```
    