Ah, OK. Took me a minute to realize this was verbose only and I needed to add `--verbose` flag to grunt. Is this something that gets run on a server and we're worried about Travis clutter? Or should we just write these out to stdout and not worry about forcing verbose?

Also, I made a few tweaks locally to make it a bit easier to read on my old eyes. Feel free to disregard.
Basically just adds some bonus indenting and removes the trailing comma (since I was confusing it w/ string output). Possibly just cleaner to put the spaces or tabs up in the `Object.keys()` loop above in lines 43 and 48

```javascript
          grunt.verbose.writeln('- Missing strings:');
          grunt.verbose.writeln('    ' + getMissingStrings(src).join('\n    ') + '\n');
```