Separate xCAT-specific code into generate_image_xcat
Add initial support for generating images with rinse
Extend the packing code to handle the rinse backend
Disable the rinse cache
Add initial support for root and boot disk partitions in fstab for supporting backends.
Clean up output messages from make_addon and run_step
Set ADDON_NAME at the beginning of make_addon
Use loop-mounted ext4 filesystems for addon scratch area