Remove hardcoding of 4.3.10 version

Allow use against any (latest) Virtualbox 4.3.x.
Also avoid littering of downloaded extension pack file

Signed-off-by: Esben Haabendal <esben@haabendal.dk>
Use /dev/vboxdrv from host and don't bother with kernel upgrading

The Virtualbox kernel module should be installed and loaded on host, and
then mounted as volume in guest container.

Signed-off-by: Esben Haabendal <esben@haabendal.dk>
DEBIAN_FRONTEND=noninteractive

Signed-off-by: Esben Haabendal <esben@haabendal.dk>
Add Emacs littering to gitignore

Signed-off-by: Esben Haabendal <esben@haabendal.dk>