Fixed urls in output when accessing front-end via https

no issue

- `vhost` as used in b46f9b1dc2 does not pass down the `trust proxy` setting to child apps so it's required to be called explicitly in each child app
- fixed URLs being output as http:// instead of https:// when the front-end is accessed with `x-forwarded-proto: 'https'`

core/server/web/site/app.js

@@ -64,6 +64,11 @@ module.exports = function setupSiteApp(options = {}) {
 
     const siteApp = express();
 
+    // Make sure 'req.secure' is valid for proxied requests
+    // (X-Forwarded-Proto header will be checked, if present)
+    // NB: required here because it's not passed down via vhost
+    siteApp.enable('trust proxy');
+
     // ## App - specific code
     // set the view engine
     siteApp.set('view engine', 'hbs');