(#240) Fix up Download Data page

This fixes issue #240.

There is one tiny little annoyance left, which is that the jQuery accordions now expand too big and then snap back to the correct size. This all happens in a fraction of a second, and I don't know off the top of my head how to fix it. So I'll create a separate issue for this that can wait until after launch.

Also, we'll need to make sure the actual data files are in place to be downloaded. I'll make sure there's a pre-launch issue for that too.