Add small demo downloads

[inc0der]

The setup guide should ask if the user would like to download small demo games that will be used for plugin development.

• Will need method to download the demos, preferably with both demo games on a LunaTechsDev repository that will always be available to download from and update easily.

• The demo games should probably be zipped, in which case we will need to extract the contents of the archive.

• Prompt user and ask if they want to download small demo games.