Add stub methods for customize, generate_cdl, generate_install_media.
Add stub methods for customize, generate_cdl, generate_install_media.

In case the underlying OS driver is not fully functional yet,
make sure to raise intelligent errors.

Signed-off-by: Chris Lalancette <60b62644009db6b194cc0445b64e9b27bb26433a@redhat.com>

ndonegan/oz,NeilBryant/oz,cernops/oz,ndonegan/oz,mgagne/oz,mgagne/oz,imcleod/oz,nullr0ute/oz,imcleod/oz,clalancette/oz,moofrank/oz,NeilBryant/oz,nullr0ute/oz,moofrank/oz,clalancette/oz,cernops/oz