Revert 601dfd9 (which removed images from atom feed if a project had …

…no image)

While technically correct, we use some external services that rely on
an image enclosure to be in place, so just for consistency, we'll
always include an image, even if it's the placeholder.

app/views/funded_projects/index.xml.builder

@@ -7,7 +7,7 @@ atom_feed(language: I18n.locale) do |feed|
       entry.title "#{project.chapter.name} – #{project.title}"
       entry.content(project.funded_description, type: 'html')
 
-      if project.has_images? && mime_type = MIME::Types.type_for(project.primary_image.url).first
+      if mime_type = MIME::Types.type_for(project.primary_image.url).first
         entry.link(href: image_url(project.primary_image.url), rel: 'enclosure', type: mime_type)
       end