Update and migrate existing tests to the `DockerHubPullSuite`. Most
tests were preserved, but refactored and made more exhaustive. One test
was deliberately removed (`TestPullVerified`) as it is unreliable and
that the feature was obsoleted by content trust.
Move all trust related tests to `docker_cli_pull_trusted_test.go`.
Move tests depending on a local registry to `docker_cli_pull_local_test.go`.
Signed-off-by: Arnaud Porterie <arnaud.porterie@docker.com>
Arnaud Porterie