Fedora 19 GRUB

In the 52-force-text-mode-console hook, gracefully exit when the
/boot/grub2 directory does not exist on the Fedora 19 cloud image
filesystem. By default the Fedora 19 cloud image is using extlinux to boot
the image instead of GRUB. The decision was taken because GRUB is quite
big (would pull in ~30MB of dependencies) and there's very little benefit
in using it because cloud images don't need to cover all the corner cases.

Change-Id: I52723d4d14c21b1787b4c7e0dd21a09cdbdae0d1