Stabilize logically bound images

[cgwalters]

The feature is working as is and provides a lot of value, so let's stabilize it.

Closes: #128

[vrothberg]

LGTM

I still believe that one config file would be great for the UX. When managing many images at once, I believe it's just easier to manage than individual .image files.

Edit: But this can be added as an extension later on if needed.

[cgwalters]

I still believe that one config file would be great for the UX. When managing many images at once, I believe it's just easier to manage than individual .image files.

I think if we were to do something here I'd probably say instead #833 which would be a lot more invasive, but also solve more problems.