Photo upload work in progress

I'd define a method like `Photo#gallery_fill_url` thus:

```ruby
class Photo < ActiveRecord::Base
  def gallery_fill_url
    picture.gallery_fill.url
  end
end
```

Not only does this make the code more readable, but it (potentially) isolates your front-end code from future changes to how the image URLs are generated.  You'd only need to modify `Photo#gallery_fill_url` to return the newly correct thing.

This is the idea behind http://en.wikipedia.org/wiki/Law_of_Demeter