Improve the default checkout order summary

Bojan - can you provide some more clarity here? What specific items would like to see improved?

This issue actually still exists in the 3.x branch and is even worse, including not even the images, just the rendered entity.

Was a bit more complicated than I hoped, because you can only override configuration provided by other modules from an installation profile's default config. That means I had to solve this in Commerce Kickstart itself rather than Commerce Demo. This is ok, though, because we already defined the product images field I wanted to rely on in the Commerce Kickstart Product module. I simply moved that up to be defined in the installation profile itself and then provided a custom version of the checkout order summary View that looks much better.

Committed.