Revert "Upgrade EE to 3.0.4, removing obsolete volumes"

This reverts commit 01dc91d.

The upgrade did not go through a public beta test and therefore is
unsuitable for release.

docker-compose.frontend.yml

@@ -108,7 +108,7 @@ services:
           - nginx.internal
 
   enketo_express:
-    image: kobotoolbox/enketo-express-extra-widgets:3.0.4
+    image: kobotoolbox/enketo-express-extra-widgets:2.8.1
     env_file:
       - ../kobo-env/envfile.txt
     environment:
@@ -119,6 +119,10 @@ services:
       # Override Enketo Express icons.
       - ./enketo_express/favicon.ico:/srv/src/enketo_express/public/images/favicon.ico:ro
       - ./enketo_express/icon_180x180.png:/srv/src/enketo_express/public/images/icon_180x180.png:ro
+      - ./.vols/enketo_express/checksum:/srv/src/enketo_express/checksum
+      - ./.vols/enketo_express/build/css:/srv/src/enketo_express/public/css
+      - ./.vols/enketo_express/build/js:/srv/src/enketo_express/public/js/build
+      - ./.vols/enketo_express/build/locales:/srv/src/enketo_express/locales/build
     networks:
       kobo-fe-network:
         aliases: