network.Address is a wrapper around multiaddress. Multiaddress
can be resolved to ip netaddr with `IPAddrString` function:
/dns4/localhost/tcp/8080 => 127.0.0.1:8080
With `HostAddrString` multi address will be transformed to
host address:
/dns4/localhost/tcp8080 => localhost:8080
Signed-off-by: Alex Vanin <alexey@nspcc.ru>
