Show image status in list output

[nightfurys]

Starting anchore-engine v0.8.0 image deletion is performed asynchronously, wherein the image status reflects the progress of the image through the cleanup workflow. Currently anchore-cli does not expose this attribute in image listing output. It didn't matter as much when the image deletion was synchronous i.e. successful delete response meant the image would no longer be included in the list. With image deletion performed asynchronously in anchore-engine, the image may continue to be included in the listings/summary views and clients such as anchore-cli should include the image status for clarity and accuracy

[dakaneye]

@nightfurys &/or @zhill did we come to a conclusion on this? Seems trivial to add the new field to the output, as discussed in the linked / closed PR, but @nightfurys comment seemed to suggest combining the analysis_status/image_status fields to be more unified and less confusing to the user?