Kontrast Cleanup

Work In Progress!

Since this is now being used internally, I don't want to commit to master anymore.
This pull request is to prepare Kontrast for public release.

Feature todo:
- [ ] Config file generator
- [ ] Rails detection
- [ ] Move non-zero diffs to the top of the gallery
- [ ] Sort the rest of the gallery into a more meaningful order
- [ ] Parallelize selenium and image handling via workers
- [ ] Figure out how to make remote integration and uploading nicer

Administrative todo:
- [ ] Update README
- [ ] Confirm license
- [ ] Write blog post
- [ ] Publish gem