wicd: get closer to upstream service definition

taken from
http://bazaar.launchpad.net/~wicd-devel/wicd/experimental/view/head:/other/wicd.service

nixos/modules/services/networking/wicd.nix

···
     environment.systemPackages = [pkgs.wicd];
 
     systemd.services.wicd = {
-      after = [ "network-interfaces.target" ];
+      after = [ "network-pre.target" ];
+      before = [ "network.target" ];
+      wants = [ "network.target" ];
       wantedBy = [ "multi-user.target" ];
       script = "${pkgs.wicd}/sbin/wicd -f";
     };