seo: increase sitemap coverage.

Rework sitemaps to provide more coverage of the site. We want every
important page on the site - including every post, tag, and wiki page -
to be indexed by Google. We do this by generating sitemaps and sitemap
indexes that contain links to every important page on the site.

test/functional/pools_controller_test.rb

@@ -23,6 +23,13 @@ class PoolsControllerTest < ActionDispatch::IntegrationTest
         get pools_path, params: {:search => {:name_matches => @pool.name}}
         assert_response :success
       end
+
+      should "render for a sitemap" do
+        get pools_path(format: :sitemap)
+        assert_response :success
+        assert_equal(Pool.count, response.parsed_body.css("urlset url loc").size)
+      end
+
     end
 
     context "show action" do