Add script to randomize VON's splash image

[jtcchan]

Just creating an issue so I have an ID to reference in my commits. This is for the feature request about randomly selecting hero images on the home page.

Relevant quote:

Also wondering - but don't do this yet. Is it easy to have the image on the main screen randomly selected? We just use a set of comparable images from the set and randomly select/display one from the set. It's a variation on the side scroll set of images. In this case, we aren't saying anything different, just showing different aspects of the impact. Or is that just a Bad Idea? :-)