Network metadata/metrics compatible with older server versions Fixes #128

This probably needs some refactoring, but it sets the iface for windows network metrics and is compatible with older versions of windows server

This is currently running on ny-web01 pointing to dev bosun. See os.net.bytes at http://goo.gl/80uLzZ

Is there any reason this would be expected to fail? Like it only works on certain windows systems? If so, we should not print the error.