Fix ActiveModel I18n integration.
Fix ActiveModel I18n integration.

#i18n_scope has to be a class method, not an instance method. Furthermore,
ActiveModel::Naming looks for #lookup_ancestors which can be mixed in with
ActiveModel::Translation. This enables localization of model names via
'Model.model_name.human' using the I18n key 'data_mapper.models.model'.

datamapper/dm-rails