Go back to using docker exec in cloudron exec

The main issue is that multiple cloudron exec sessions do not
share the same rootfs. Which makes it annoying to debug.

We also have some nginx timeout which drops you out of exec
now and then resulting in loss of all state.

src/docker.js

@@ -159,7 +159,7 @@ function createSubcontainer(app, name, cmd, options, callback) {
     var memoryLimit = manifest.memoryLimit || (developmentMode ? 0 : 1024 * 1024 * 200); // 200mb by default
     // for subcontainers, this should ideally be false. but docker does not allow network sharing if the app container is not running
     // this means cloudron exec does not work
-    var isolatedNetworkNs = isAppContainer || !developmentMode;
+    var isolatedNetworkNs = true;
 
     addons.getEnvironment(app, function (error, addonEnv) {
         if (error) return callback(new Error('Error getting addon environment : ' + error));