Refs #490, "Add Members" section for course groups is now visible in IE8.

I could see the code in "view source" in IE8, it just wasn't showing on the page. So I ran the HTML through the W3C validator and one of the validation issues was that the second column was never used; the table had a a <colgroup /> with 3 <col /> tags, but the first <td /> ALWAYS had a colspan of at least 2, so the second column essentially wasn't being used. Removing the unused column and decrementing all the colspans on that table fixed that issue.