New VirtualBox basebox

Hey,

I created a new basebox for virtualbox users containing extension version 4.3.12.
For some other (minor) changes see https://github.com/fadenb/bento/compare/fadenb:ca9f08be8861143b1cac36cd8fad5ec824772bc1...59316cddcdb593a0622731c5574658480ad8d1c1


It is working fine on my system but I would love someone to do some more testing before switching boxes.