As people are using the UUID in `docker info` that was based on the v1 manifest signing key, replace
with a UUID instead.
Remove deprecated `--disable-legacy-registry` option that was scheduled to be removed in 18.03.
Signed-off-by: Justin Cormack <justin.cormack@docker.com>
In info, we only need the number of images, but `CountImages` was
getting the whole map of images and then grabbing the length from that.
This causes a lot of unnecessary CPU usage and memory allocations, which
increases with O(n) on the number of images.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
