catch exception on malformed JSON
vbox+kvm2usb: implement stop+cont+do_{save|load|del}vm
adapt video timings for vaio/nvidia
use empty desktop needle for x11 tests

the method with the pre and post image turned out to be impractical as different things change on different desktops. The ui can't give a proper clue what's wrong with the pre and post images. By waiting on the needle the problem is clear.
comment old code
disable waiting for reboot-after-installation

the meaning of reboot-after-installation is unclear. It's used in grub as well as 2nd stage automatic configuration. And then ere is also reboot_after_install from 800_reboot_after_install.pm