Disable fallback on class level

[MSchmidt]

We can already disable fallbacks on instance level:

I18n.locale = :en
post.title_nl # => This database rocks!

post.disable_fallback do
  post.title_nl # => nil
end

But especially for the mentioned use case of admin panels, wouldn't it be better to disable everything on class level? This way we could disable fallbacks for everything in some kind of AdminController.

JSONTranslate.disable_fallback do
  # ...
end