ShareUrl: Dynamically created by client for proxies

Made the client contruct the shareUrl, to account for the use of
proxies. Now the server sends the client only its ip, and the endpoint.
The client then constructs the shareUrl link by getting the same url he
is connected to. If the url is "localhost" though, he will use the "ip"
sent by the server (since most people connect with "localhost", but want
to have a function share link).