Issue #10: Changed the student image to render as a colorbox

This allows somebody to click the thumbnail and bring up a
colorbox with the full-size image. I don't know that it will be
something that a lot of people will do, but it's trivial to make
happen, and I don't see a real reason not to add that feature.

Signed-off-by: Elliot Voris <elliotfriend@gmail.com>