standardize on localhost for local server's name

I think localhost should be the default value for the local server. This seems more intuitive. This also allows a user to input None for the server, and and it will set the server to 'localhost' instead to stay consistent. 

Also, instead of checking the interface ip address of eth0, we can simply resolve the name 'localhost' just as we resolve the other server ip addresses. This removes the possibly confusing issue if eth0 is not present on the system, and removes the dependency entirely for an interface name.