Refactor to tidy up code

A little presumptive of me, but I thought I found a bug and in working through the code I did some refactoring that I think has removed some unnecessary code. I think my refactor is worth pulling in, as I think it makes the code more readable. However, it doesn't alter the functionality.

So please feel free to gleefully reject this pull request.

I thought I spotted a bug around the way domains are grabbed from the config, but now I've played around I can see why its done the way it is.

I still feel putting the output files into the same folder as the input files on image compare and relying on a sort by file name to pull out the right files, is prone to future problems. The files are created by the app, so the app should be able to track the file names used, and therefore remove the need to find files via sort. That might also remove the need to clear out the shots file each time the app is run.