Add CACHE_URL now needed by kpi and kobocat beta

see:
- kobotoolbox/kpi#3862
- kobotoolbox/kobocat#833
- kobotoolbox/kobo-install#193
- kobotoolbox/kobo-docker@cdcdbe697cb911e9 ...

envfile

@@ -7,6 +7,7 @@ export SKIP_CELERY=True
 export REDIS_SESSION_URL=redis://:[email protected]:60667/0
 export KPI_BROKER_URL=redis://:[email protected]:60667/1
 export KOBOCAT_BROKER_URL=redis://:[email protected]:60667/10
+export CACHE_URL=redis://:[email protected]:60667/5
 
 export KOBOFORM_INTERNAL_URL="http://$IP:9000"
 export KOBOFORM_URL="$KOBOFORM_INTERNAL_URL"