Add a CLI flag for deleting locally cached images upon container removal #225
Description
When removing a container with kanto-cm CLI, it should be possible to delete the locally cached container image. Currently the deletion of the images is handled by the image_expiry and image_expiry_disable configurations of the daemon. The new flag should be prioritized over the daemon configurations. If the image is used in a container, the cache must remain and appropriate message be displayed to the CLI user.