WIP feat(signup): suggest proper email spelling

Fixes #871.
Translation would go something like this:
```js
function t(str, params) {
  return view.translator.interpolate(view.translator.get(str), params);
}

....

message: t('Did you mean <span>%(domain)s</span>?', suggestion)
```

It might be wort adding a helper method like `t` to the view, e.g. `view.t('oh hai', params)`.