Could have some interaction with #832

Currently, we import the imagefactory libs and call their functions, effectively handing over control to another tool. This means that the koji code isn't really running at this time, so there is nothing to do this upload (I don't think imagefactory needs to be aware of koji).

Likely this will mean forking off a process for imagefactory, and then monitoring both it and the logs in the original task process.

Or perhaps there is an imagefactory callback? (If not, I don't think adding one is the way)

Frankly, probably better to get imagefactory into it's own process for other reasons too.

Note: putting this in a separate process doesn't mean we have to exec imagefactory instead of calling it. That would be a big refactor, but we could probably introduce a fork in the existing code without too much disruption.

Dropping - we don't want to invest too much into image builds.