Make unbound reply on cloudron network

Because of the docker upgrade, dnsbl queries are failing again
since we are not using the unbound server from the containers.

For some reason, docker cannot query 127.0.0.1 (https://github.com/docker/docker/issues/14627).

Make unbound listed on the cloudron network and let docker proxy
DNS calls to unbound (docker always use the embedded DNS server
when using UDN).

See also #130

src/platform.js

@@ -55,7 +55,6 @@ function initialize(callback) {
 
     async.series([
         stopContainers.bind(null, existingInfra),
-        createDockerNetwork,
         startAddons.bind(null, existingInfra),
         removeOldImages,
         startApps.bind(null, existingInfra),
@@ -117,10 +116,6 @@ function stopContainers(existingInfra, callback) {
     callback();
 }
 
-function createDockerNetwork(callback) {
-    shell.execSync('createDockerNetwork', 'docker network create --subnet=172.18.0.0/16 cloudron || true', callback);
-}
-
 function startGraphite(callback) {
     const tag = infra.images.graphite.tag;
     const dataDir = paths.DATA_DIR;