Use rastasheep/ubuntu-sshd as base image

Signed-off-by: Esben Haabendal <esben@haabendal.dk>
Drop /vbox volume as there is no obvious use for it

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

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