In order that something consuming an artifact can have access to extra
builder specific data add the State method which allows the caller to
ask for arbitary values by name.
The null builder is not really a bulider, it just setups a SSH
connection and runs the provisioners. It can be used to debug
provisioners without incurring high wait times. It does not create any
kind of image or artifact.
Julian Phillips
Florian Noeding
Mitchell Hashimoto
Ross Smith II