Usability of pulling images

[deboer-tim]

When we use API to pull an image, there's no task or progress associated with it. If you leave the page and come back, we have no history that you're still pulling the image in the background, until it magically appears.

Explore if the API should be triggering a task, or we need to create a wrapper. See if we can query whether an image is being pulled, or should keep a store of the ones we know about so that we can keep state when you leave a page and return.