When building the base images always test signatures.
This will be the default at some point.
Add a test that content trust is working.
Signed-off-by: Justin Cormack <justin.cormack@docker.com>
Simpler to have an image that takes the kernel and initrd as input,
rather than building them into the image.
The rest need converting.
Signed-off-by: Justin Cormack <justin.cormack@docker.com>
