Fix #2502: tls self_signed not working correctly

[abiosoft]

Fixes #2502: tls self_signed not working correctly.

Having compared the code changes with older Caddy versions, I am not sure exactly what changed.
However, I think this is supposed to be the expected behaviour.

Previously #2511.

[thattomperson]

From godoc.org/crypto/tls

TLS 1.3 is available only on an opt-in basis in Go 1.12. To enable it, set the GODEBUG environment variable (comma-separated key=value options) such that it includes "tls13=1". To enable it from within the process, set the environment variable before any use of TLS:

And it looks like Appveyor is using golang v1.11

[elcore]

@thattomperson

TLS 1.3 is available only on an opt-in basis in Go 1.12. To enable it, set the GODEBUG environment variable (comma-separated key=value options) such that it includes "tls13=1". To enable it from within the process, set the environment variable before any use of TLS

Caddy does that for you

https://github.com/mholt/caddy/blob/72d0debde6bf01b5fdce0a4f3dc2b35cba28241a/caddytls/setup.go#L37-L39

And it looks like Appveyor is using golang v1.11

We know, we are waiting for an update...

[mholt]

I do not think this is the right approach... if the hostname is empty (e.g. "catch-all" address like :2015), we need to serve for ALL addresses, not just local ones.