Use Dropbox storage selectively -- only for production (Heroku).
Add image validation line (now required) to development instructions of using images (not dropbox instructions, but still needs validation.
Organize Dropbox stored images by putting in folders by size AND making sure each image is unique by renaming it by :id (so it will look like :id_:filename) in Dropbox.
Clean up comments. Heroku should be running with Dropbox (if all previous listings were deleted. Can create new listings.)
testing moving pg gem exclusively into production.