nixos/vbox: Move all options to virtualisation.*.

Commit 687caeb renamed services.virtualboxHost to programs.virtualbox,
but according to the discussion on the commit, it's probably a better to
put it into virtualisation.virtualbox instead.

The discussion can be found here:

https://github.com/NixOS/nixpkgs/commit/687caeb#commitcomment-12664978

Signed-off-by: aszlig <aszlig@redmoonstudios.org>

nixos/tests/virtualbox.nix

@@ -31,7 +31,7 @@ import ./make-test.nix ({ pkgs, ... }: with pkgs.lib; let
       fsType = "vboxsf";
     };
 
-    services.virtualboxGuest.enable = true;
+    virtualisation.virtualbox.guest.enable = true;
 
     boot.initrd.kernelModules = [
       "af_packet" "vboxsf"
@@ -308,9 +308,9 @@ in {
       vmConfigs = mapAttrsToList mkVMConf vboxVMs;
     in [ ./common/user-account.nix ./common/x11.nix ] ++ vmConfigs;
     virtualisation.memorySize = 768;
-    services.virtualboxHost.enable = true;
+    virtualisation.virtualbox.host.enable = true;
     users.extraUsers.alice.extraGroups = let
-      inherit (config.services.virtualboxHost) enableHardening;
+      inherit (config.virtualisation.virtualbox.host) enableHardening;
     in lib.mkIf enableHardening (lib.singleton "vboxusers");
   };