add column attributes

[ngaugler]

I'm using dataTables and I need to be able to add attributes to each column that have data based on the row data (data-order="renderedColumn"). It might make sense to move getClasses into the attributes to clean up the code, but I leave that up to you.

[gbrock]

I like the idea, but as you said I'll need to alter a couple of things so it won't potentially interfere with the existing classes methods. This will likely appear in a future version, thank you for contributing.