Use SNI & begin verifying HTTPS certificates

[rollerozxa]

Currently the game doesn't verify HTTPS certificates because it doesn't use SNI to specify to the server which host it is connecting to. So when it connects to https://principia-web.se it receives the self-signed certificate on https://51.68.173.17 instead of the proper principia-web certificate signed by Let's Encrypt.

I could fiddle with my certificates on the server side, but it's better if this got fixed in the client.