Set default for client.dns.lookup to use_all_dns_ips

The default setting of the configuration parameter client.dns.lookup is not use_all_dns_ips .  Consequently, by default, if there are multiple IP addresses and the first one fails, the connection will fail.

It is desirable to change the default to be client.dns.lookup=use_all_dns_ips for two reasons:

1. reduce connection failure rates by 
2. users are often surprised that this is not already the default