web: add ability to disable HTTPS

If TLS is terminated elsewhere and then connections are proxied over
HTTP, there is no need for it and it makes initialization a tad slower
on the first run.

docker-compose.yml

@@ -13,6 +13,7 @@ services:
             - ENABLE_AUTH
             - ENABLE_GUESTS
             - ENABLE_LETSENCRYPT
+            - DISABLE_HTTPS
             - JICOFO_AUTH_USER
             - LETSENCRYPT_DOMAIN
             - LETSENCRYPT_EMAIL