Read from the old translations.txt.

def _read_translations(self):
        """Read from the old translations.txt.
        """
        print('Reading original translations')
        self.translations_map = {}
        n_translations = 0
        with open(os.path.join(self.src_dir, 'translations.txt'),
                  'rb') as csvfile:
            reader = csv.DictReader(csvfile)
            for row in reader:
                self.translations_map.setdefault(
                    row['trans_id'], {})[row['lang']] = row['translation']
                n_translations += 1
        print('\ttotal original translations: %s' % n_translations)