added sni tests

[sarge]

Expanding the SNI tests.

Ideally with an SNI less connection we don't to know the destination IP address, things in the cloud are load balanced, DNS changes.

This change supports this port only matching configuration

 {
    http_port     9080
    https_port    9443
    default_sni   a.caddy.localhost
  }

:9443 {
    tls /a.caddy.localhost.crt /a.caddy.localhost.key {
    }
    respond /version 200 {
      body "hello from a.caddy.localhost"
    }	
}

The configuration I would like to support is

 {
    http_port     9080
    https_port    9443
    default_sni   a.caddy.localhost
  }

 a.caddy.localhost:9443 {
    tls /a.caddy.localhost.crt /a.caddy.localhost.key {
    }
    respond /version 200 {
      body "hello from a.caddy.localhost"
    }	
  }

Which would respond to curl https://127.0.0.1/version. In this case the CP matches perfectly but the host matcher does not.

I guess an alternative could be, with a wildcard IP matcher.

 a.caddy.localhost:9443, 0.0.0.0:9443 {
    tls /a.caddy.localhost.crt /a.caddy.localhost.key {
    }
    respond /version 200 {
      body "hello from a.caddy.localhost"
    }	
  }

[mholt]

Cool, so should we merge this?