Reusable server url

Improve the re-usability of the addQueryArg() method

- Support SSL protocol
- Make the serverUrl code re-usable
No, we can't. The method is static so it only has access to static properties.
Passing `$this->serverUrl` in via the $url parameter would be good practice in the cases that's applicable.

Also: I'd advocate for leaving the method as static so you don't have to pass the updateServer object to other classes to have access to this method.