fix truncation of image name in grub
fix Makefile to rebuild box when .vmdk changes
allow overridding TMPFS_SIZE
allow disabling use of tmpfs via NO_TMPFS=1

Despite significantly reducing the build time, tmpfs does
seem prone to kernel bugs, so better make it optional.
eliminate duplication between box creation Makefiles
add main() to allow full refactoring
eliminate duplication between build-image.sh files
rename admin node image name in grub for clarity
switch from IDE to SCSI disks and add DRBD
generate config.xml from template

This allows us to eliminate hardcoding of paths within config.xml.