Allow DNS resolution of `--host` flag
In order to simplify setups, it would be *very* nice if we could specify the host via DNS.

Not only does this simplify using your own remote node, it also greatly simplifies any Docker setup as you can simply connect `p2pool` and `monerod` via container name no matter what IP address it gets.

As an example, if `--host` allowed DNS resolution, the following compose file would be all you need to spin up `monerod` and `p2pool` with almost no other configuration:

https://github.com/sethsimmons/p2pool-docker/blob/main/examples/docker-compose.yml

Thanks in advance!