bb.org: i test with the bone-debian image a lot, bump to 4gb by default

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>
legacy: leaving ./beagleboard.org_image.sh for new users

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>
cleanup: ./beagleboard.org_image.sh too small for a copyright header

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>