create core script directory

Signed-off-by: Sebastien Varrette <sebastien.varrette@uni.lu>
use environmental variables in motd

Signed-off-by: Sebastien Varrette <sebastien.varrette@uni.lu>
set cache dir for packer on build

Signed-off-by: Sebastien Varrette <sebastien.varrette@uni.lu>
start to embed librarian-puppet provisioning in packer build

Signed-off-by: Sebastien Varrette <sebastien.varrette@uni.lu>
complete librarian-puppet

Signed-off-by: Sebastien Varrette <sebastien.varrette@uni.lu>
complete README

Signed-off-by: Sebastien Varrette <sebastien.varrette@uni.lu>