builder/parallels: Attach ISO images to the default cdrom device

Attach the primary ISO to the default cdrom but restore it in the end.
If Parallels Tools ISO is attached it will be to a new cdrom device
which will be deleted in the end.

Related to: [mitchellh/packer#1502]
Merge pull request #2 from rickard-von-essen/remove_step_remove_devices

builder/parallels: Attach ISO images to the default cdrom device
Revert "builder/parallels: Attach ISO images to the default cdrom device"

This reverts commit ec9591775e82ea75282c7895ce2ff19f6c540387.
builder/parallels: Disable default cdrom0 device and then enable it on cleanup

This is needed to make 'cdrom0' device unavailable during the ISO installation process.
It is required for some guest OS types, such as FreeBSD and OmniOS.
Merge pull request #4 from legal90/remove_step_remove_devices

Disable 'cdrom0' device while ISO installation