fix column-wrapping issue

There was an issue where the items on the command page would wrap to the next column. It seems to be due to the fact that each `<li>` in a column is not necessarily the same height. Their calculated height is also not an integer which is closely related to this issue.

There are a few ways to fix this, but if we're using CSS columns, the property I'm adding here seems to be the clearest solution.

See screenshot for example of wrapping issue – notice the little visible pieces of list items at the bottom of the screenshot. Those are items that ultimately wrap to the next column.

![screen shot 2013-10-12 at 3 20 14 pm](https://f.cloud.github.com/assets/197309/1320723/5f3241a6-3373-11e3-97d8-e8022a39c140.png)