**WIP** Home sprite

This is a work in progress until the other PRs are merged and in case @jasonlong provides better resized images to use for the sprite but it should be ready for testing.


Notes:
* I didn't remove the individual images from the repository although they are unused now.
* I went with the `span` approach for the sprite classes. It seems to work fine in all browsers I could test, but if anyone has a better idea let me know.