Improve Progress messages during docker operations

[dexhorthy]

Better progress message detail during docker operations, include image name

What I Did

Improve progress messages during docker operations in render step.

How I Did it

• Add image field to images.Progress
• Send image down to client
• Client reads image and other status fields
• Client shows layer name under progress bar
• Add debug logging during docker pull

How to verify it

Run a ship yaml with a

assets:
  v1:
  - docker:
      image: postgres:9.6
      dest: ./postgres.tar
lifecycle:
  v1:
    - render {}

See fancy messages on render step.

Description for the Changelog

Improve progress messages during docker operations in render step.

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