Bugfixed

According to @marmarek's request

qubesmanager/create_new_vm.py

@@ -123,7 +123,7 @@ class NewVmDlg(QtGui.QDialog, Ui_NewVMDlg):
         properties['netvm'] = self.netvm_list[self.netvm.currentIndex()]
         if self.install_system.isChecked():
             properties['virt_mode'] = 'hvm'
-            properties['kernel'] = 'none'
+            properties['kernel'] = None
 
         thread_monitor = ThreadMonitor()
         thread = threading.Thread(target=self.do_create_vm,