Add settings.uiHost - to allow binding to a specific interface

Closes #58

settings.js

@@ -15,6 +15,12 @@
  **/
 module.exports = {
     uiPort: 1880,
+    
+    // By default, the Node-RED UI accepts connections on all IPv4 interfaces.
+    // The following property can be used to listen on a specific interface. For
+    // example, the following would only allow connections from the local machine. 
+    //uiHost: "127.0.0.1",
+    
     mqttReconnectTime: 15000,
     serialReconnectTime: 15000,
     debugMaxLength: 1000,