Don't pass brackets to getaddrinfo() for IPv6 nodes

Passing the brackets will always return a "Name or service not known"
error from getaddrinfo() when specifying an IPv6 address.
Always show numeric address in "Listening on" message

Without this flag, getnameinfo() will translate a listener of [::1] to a
name and we then show an invalid URL such as:
"Listening on http://[localhost.localdomain]:8080."