Allow resume from hibernation

[NeroReflex]

This PR is aimed at appending to kernel boot parameters the btrfs offset and uuid of the file /home/swapfile when such file is present.

This in turn allows an initramfs that was generated with mkinitcpio containtaining the "resume" hook so resume from hibernation.

This PR is therefore required to support sleeping consoles that only supports S5 status.

[alkazar]

Very nice. But I don't think this will work after install since the swapfile does not exist yet. It is created by a service on first boot.