subtests.docker_cli.ps_size: Fix the base class name

There was copy&paste error.

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
subtests.docker_cli: Add images --all test

this test focuses on differences between `docker images` and
`docker images --all`. Additionally it checks the image history and
verifies the automatic cleanup of untagged unused images.

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
subtests.docker_cli.images_all: Add variant with background containers

Sometimes docker rmi is confused when there are existing containers.
This variant creates 10 background containers and then run the test.

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
Merge pull request #293 from ldoktor/images_all

subtests.docker_cli: Add images --all test