Use "." instead of "source" (source doesn't seem to be POSIX compatible.
E.g. fails on Ubuntu where /bin/sh is mapped to dash)
load vars.sh via "." instead of "source" in cleanup script
remove -j option from date command
parameterize vars for easier override and change
Check for existence of isos and boxes dir
Use BOXES_DIR var instead of harcoded path
Update README for overriding some directory variables
README - update guest additions version in the example
Fix vbguest iso filename