The "[[ ... ]]" syntax is bash-specific. Reflect this by changing shbang to "#!/bin/bash". Many of our dev systems symlink "/bin/sh" to "/bin/bash" which has masked this problem for a long time, but "real" sh fails on "[[".
BUG=none
TEST=rerun
Review URL: http://codereview.chromium.org/2825050
Remove the temporary rootfs.image file and others that are left by build_image and related scripts. Also added tool to emit scripts that can pack and unpack the combined disk image.
Review URL: http://codereview.chromium.org/1567013