More flexible version of `wildcardDNS`

[jglick]

#178 is useful but does not work with http://readme.localtest.me/ which is nicer not just because it makes for shorter URLs but because it automatically serves ::1 (IPv6) as well as 127.0.0.1. Should deprecate the original parameter and introduce a variant that does not add the 127.0.0.1. infix so you could set it to localtest.me. You could still use 127.0.0.1.nip.io or 127.0.0.1.xip.io or whatever.