The `digest` data type, used throughout docker for image verification
and identity, has been broken out into `opencontainers/go-digest`. This
PR updates the dependencies and moves uses over to the new type.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
Move configurations into a single file.
Abstract download manager in pull config.
Add supports for schema2 only and schema2 type checking.
Add interface for providing push layers.
Abstract image store to generically handle configurations.
Signed-off-by: Derek McGowan <derek@mcgstyle.net>