Add <img> tags for all thumbnails to the photos list entry. I'm hoping with lazy
loading and some JavaScript this will not be terrible!
Break the logic for preparing a thumbnail into a separate helper partial
template so it can be reused.
- Move photo_thumbnail.html to photos/thumbnail.html
- Add a photos/list.html partial that returns a list of photos for the current
page
- Use the template above everywhere we need a list of photos for the page
