Improve the FuncUnit.com build

You can run `make` to build & deploy the FuncUnit site, but the way it works seems like a hack:

- The `site` folder has its own [Makefile](https://github.com/bitovi/funcunit/blob/990337b91ab927662daf83c1b4e3f6b5c0ece538/site/Makefile) and [package.json](https://github.com/bitovi/funcunit/blob/990337b91ab927662daf83c1b4e3f6b5c0ece538/site/package.json), which seems odd
- [At least one file is force-added unnecessarily](https://github.com/bitovi/funcunit/blob/990337b91ab927662daf83c1b4e3f6b5c0ece538/Makefile#L15) (that whole script could probably use some attention/verification)
- Static resources are loaded from different folders, depending on which main section you’re on (i.e. the home page loads resources from `site/static`, while the Guides page loads from `guides/static`)

Home page:

Guides page: