Options disabled in wizard should be disabled in setting tab

[Hua Zhihao]

After creating the environment (before deploy) the settings tab lets you chose between qemu and kvm. I don't know what the deploy would do if you selected KVM, but we should disable them and preferably change 'qemu' to 'xenserver'

We also need a bug to disable some settings in the storage tab and additional components tab of a XS environment. The wizard doesn't let you select them, but the settings (pre-deployment) do.