Don’t use localStorage if there’s chrome.storage
Make the open source version work

- Move visuals to a separate visuals/ directory.
- Update templates and styles to reflect this change.
- Update README.md, add a section about releasing Chrome apps.
- Undo previous commit with regard to localStorage.
- Add the Fondamento font as the OFL allows it.

Fixes #2.
Make the packaged app work again.

We still cannot upload it to the Web Store as it does not allow
for upgrading legacy apps to packaged apps.