1. checks the localization for a few reference languages for the nav bar
2. for our localized pages (splash, about, wedo2), it checks to see that there are locale strings, whether or not they're english (to make sure at least something is on the page).
This moves all locale/translation building to a dependency, `scratch-www-intl-loader`, as well as tests associated with it. Also gets rid of the `make translations` step.