This commit introduces liveness checks to Kilo. This allows the Kilo
daemons to take nodes with inactive or dead Kilo deamons out of the
topology until they are alive again.
Today, net.Listen will only listen on 127.0.0.1 if localhost is passed
[0]. Listening on `:8080` will open a dualstack socket on OSs that
support it.
[0] https://github.com/golang/go/issues/9334
