Make host and port configurable (#94)

Use the previous values as the default.

config/default.json

@@ -2,6 +2,8 @@
   "team_name": "My Open Spacedeck",
   "contact_email": "support@example.org",
 
+  "host": "::",
+  "port": 9666,
   "endpoint": "http://localhost:9666",
   "invite_code": "top-sekrit",
 

spacedeck.js

@@ -114,9 +114,10 @@ module.exports = app;
 db.init();
 
 // START WEBSERVER
-const port = 9666;
+const host = config.get('host');
+const port = config.get('port');
 
-const server = http.Server(app).listen(port, () => {
+const server = http.Server(app).listen(port, host, () => {
   
   if ("send" in process) {
     process.send('online');