The following is a description of some of the more commonly used
variables employed during installer or live image creation.

INSTALL_GRUBCFG:      The grub configuration file used when creating an
                      installer image (unused when creating a live image).


INSTALL_ROOTFS:       The 'bare metal' rootfs image. Passed to the installer
                      when performing an install or creating a live image.


HDINSTALL_ROOTFS:     The rootfs image which will be used as the rootfs of the
                      installer (unused when creating a live image).


HDINSTALL_CONTAINERS: In the case of installer generation this is the
                      list of containers to cp to the install media,
                      This list will be copied to the installer config
                      and thus used when the installer performs an
                      install. In the case of generatiing a live image
                      this list will be the containers installed in
                      the live image. Container names can include
                      attribute suffixes.


NETWORK_DEVICE:       The network device to passthrough to the network
                      prime.  The network prime is defined by the
                      'net=1' attribute being set for a container.


GRUB_KERNEL_PARAMS:   Kernel parameters appended to the boot line used by the
                      installed or live images. (cubeit-installer, x86 only).

LOCAL_POST_FUNCTION_DEFS: Local function definitions which will be
			  sourced by the installer scripts. When
			  creating an on target installer this script
			  and any other files found in the same
			  directory will be copied to the installer
			  media.