break it out to only grab it once
add image-size module
don't set the background here
custom background support

This lets you use `background.png` in your roms dir to set a custom
background. If you don’t provide one, the default included one will be
used.

The background will be measured and any background under 600px wide
will be tiled, anything over will be stretched across the background.
Merge pull request #11 from maddox/custom-background

Custom Background