versionifier.py fetches previous versions from the github releases, caches their pages and creates links on versions.html to them.
versions.html is embeded in the main page
(Assuming you have node/npm and python installed) run npm install to install local dependancies (minify and gh-pages)
npm run build to create the build files (minifies js and gets previous versions)
or
npm run deploy to create the build files and deploy them to github pages (gh-pages branch on github)