dockertest: Adds dockercmd ability to implement other interfaces.

Signed-off-by: Jiří Župka <jzupka@redhat.com>
dockertest: Move cmd status checker to output.

Signed-off-by: Jiří Župka <jzupka@redhat.com>
subtests: Fix daemon tests to use interface without object container.

Signed-off-by: Jiří Župka <jzupka@redhat.com>
subtests: Fix some tests.

Signed-off-by: Jiří Župka <jzupka@redhat.com>