Add show actions for note, artist, artist commentary versions.

Add these endpoints:

* /note_versions/1234
* /artist_versions/1234
* /artist_commentary_versions/1234

This is so the /ip_addresses listing can link to these endpoints.

test/functional/artist_versions_controller_test.rb

@@ -3,10 +3,8 @@ require 'test_helper'
 class ArtistVersionsControllerTest < ActionDispatch::IntegrationTest
   context "An artist versions controller" do
     setup do
-      @user = FactoryBot.create(:gold_user)
-      as_user do
-        @artist = create(:artist)
-      end
+      @user = create(:gold_user)
+      @artist = as(@user) { create(:artist) }
     end
 
     should "get the index page" do
@@ -18,5 +16,15 @@ class ArtistVersionsControllerTest < ActionDispatch::IntegrationTest
       get_auth artist_versions_path(search: {name: @artist.name}), @user
       assert_response :success
     end
+
+    context "show action" do
+      should "work" do
+        get artist_version_path(@artist.versions.first)
+        assert_redirected_to artist_versions_path(search: { artist_id: @artist.id })
+
+        get artist_version_path(@artist.versions.first), as: :json
+        assert_response :success
+      end
+    end
   end
 end