The catch there before is meant to just continue if it comes across a file that doesn't exist (in which case the language will default to english). However, it was not specific enough – now, it only catches the error if the file doesn't exist, and throws anything else, preveting a build.
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.
1. Load locale strings into `window._messages` in a separate file added to `template.html`, which contains view-specific and general strings
2. Update build-locales to compile separate files
