Add translations for rails date order

Not doing so caused crashes on applications which don't fall back to
English when a translation is missing.

We're adding them in a separate file so we can exclude it from crowdin
and so translators don't translate symbols as if they were words which
need translation.

crowdin.yml

@@ -1,6 +1,8 @@
 files:
   - source: /config/locales/en/**.yml
     translation: /config/locales/%locale%/%original_file_name%
+    ignore:
+      - /config/locales/**/rails_date_order.yml
     update_option: update_without_changes
     languages_mapping:
       locale: