Adding SSL support to eventsource

[Kuckkuck]

Hi,

I have added ssl support for the eventsource to solve insecure errors, if the website is running on https.
Please check. Thanks a lot.

Regards,

Olaf

[ipmb]

Thanks for the pull request! We don't actually use this service anymore, instead leveraging the nginx-push-stream-module with Nginx (which were already using for TLS termination). Here's an example conf: https://github.com/BotBotMe/botbot-web/blob/master/nginx.conf.example