This commit complements blivet's c35aafe4b27318faee52b5a0ea44ca9a6fd4a1ec because RHEL7 doesn't support working with HFS+ partitions.
The HW boots just fine with VFAT EFI system partition. The downside of using VFAT is that there aren't pretty menus, but I prefer no menus but working system over non-working system each time.