Background image first pass

[randomPoison]

A simple first-pass background image. Keep in mind that we don't know what size screen we're going to be displaying on (and we will likely display on multiple different screens), so the background shouldn't include any elements that will look bad if stretched or cropped (e.g. don't put a border around the edge). Ideally, we'll crop the image to fit different screen sizes, and then just scale it up to fit, so the background image will never be stretched weirdly.