Support EFI hard disk installation on Macs

[aejsmith]

The EFI support works on Mac when booting from a USB device or CD, but it cannot yet be installed to a hard drive (at least it hasn't been tested). efibootmgr does not work on Mac. It may be possible to get it to work just by placing KBoot in the FAT system partition and then using the bless command from OS X.

In order to be able to boot OS X we do need to also add HFS+ support, since the OS X loader is stored on the HFS+ OS X partition rather than the EFI system partition.