Escalate missing error when :raise is true

Before ec16ba75a5493b9da972eea08bae630eba35b62f, 
`ActionView::Helpers::TranslationHelper#translate` has raised errors with 
specifying `options[:raise]` to `true`.

This should work by this fix:

   begin
     t(:"translations.missing", raise: true)
   rescue I18n::MissingTranslationData
     p :hello!
   end