make configs settable

server.go

@@ -34,9 +34,17 @@ func (s *Server) body() (httpbody, error) {
 	userdata, err := s.UserData.String()
 	body["ciuserdata"] = userdata
 	for i, n := range s.NetDevices {
+		if n == nil {
+			body["net"+strconv.Itoa(i)] = ""
+			continue
+		}
 		body["net"+strconv.Itoa(i)] = n.String()
 	}
 	for i, ip := range s.IPConfig {
+		if ip == nil {
+			body["ipconfig"+strconv.Itoa(i)] = ""
+			continue
+		}
 		body["ipconfig"+strconv.Itoa(i)] = ip.String()
 	}
 	return body, err