Artworks and Galleries

Don't merge. Todo: tests.
This is totally cool, but there might be a slightly more compact way to write this `index` method. Any thoughts on this change?

```ruby
def index
  @sort = params.fetch(:sort, 'recent')
  @artwokrs = Artwork.page(params[:page])
  @artworks = @artworks.recent if @sort == 'recent'
end
```