deploy/ci: Make vcluster use debootstrap

Introduce a new helper script, mkimage.sh that creates a debian base
raw image with debootstrap so that it can be used in a virtual
cluster.

Install network-manager and a hook to update hostname with info
provided by DHCP responce.

Add new conf setting for the size of the image.

Create another empty image as well so that the VM can use it for
LVM.

Remove unused settings.

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
deploy: Add image command

..that creates the debian base image needed by the vcluster command.

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
deploy: Support dry-run in vcluster

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
deploy: Check vcluster node's IP and subnet

..and abort if some node's IP does not reside inside the vcluster's
subnet.

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>