'Attach feed collection grouped apps (for \'mega collection\').
Sets app.group_translations to something like
[{\'lang\': \'en-US\', \'string\': \'My Group\'}].'

def _attach_group(self, app):

    if self.context.get('group_apps'):
        group_index = self.context['group_apps'].get(unicode(app['id']))
        if (group_index is None):
            group_index = self.context['group_apps'].get(app['id'])
        if (group_index is not None):
            if isinstance(app, dict):
                app.update(self.context['group_names'][group_index])
            else:
                setattr(app, 'group_translations', self.context['group_names'][group_index]['group_translations'])
    return app
