Add ability to download ROMs without logging into server

[Greyson Parrelli]

Since this is a docker container, if we make changes and push a new container, we'll also push old versions of the ROMs and lose all of our pets' progress! We should have an easy way to pull off existing ROMs.

This could be a script, but preferably the ROMs would just be available to download on the site. It could be as simple as adding a symlink to /root/roms in /var/www/html. We could even add a download button underneath each pet's screen in the web interface.