Akka 1.3.0.

The title more or less says it all - right now the IPFamily specified on the DNS endpoint isn't taken into consideration when resolving domain names and thus we treat all DnsEndPoint instances as though they are AddressFamily.Unspecified. We can use this information when it's provided by the end-user to use addresses from the explicitly requested family instead of defaulting to IPV4 / flipping to IPV6 when IPV4 fails, which is the behavior implemented since: #3063