[Login] Service might fail on installations with static IP

If an OS that boots Kodi on startup is used & a static IP is given, it might be the case that the service fails on startup & the plugin can't be started.
This happens because we "ask" the OS on startup to assign two ports for our two internal service webservers.
Getting the port `sock.getsockname()` is the weak spot here (see https://github.com/asciidisco/plugin.video.netflix/blob/master/service.py#L18), as it throws if the network isn't up at the point of excecution of that piece of code.