rails: add 'URL' inflection.

Make it so we can write `ArtistURL` instead of `ArtistUrl`.

test/functional/artist_urls_controller_test.rb

@@ -1,6 +1,6 @@
 require 'test_helper'
 
-class ArtistUrlsControllerTest < ActionDispatch::IntegrationTest
+class ArtistURLsControllerTest < ActionDispatch::IntegrationTest
   context "The artist urls controller" do
     setup do
       @artist = create(:artist, name: "bkub", url_string: "-http://bkub.com")

test/unit/artist_test.rb

@@ -152,10 +152,10 @@ class ArtistTest < ActiveSupport::TestCase
 
     should "not delete urls that have not changed" do
       artist = FactoryBot.create(:artist, :name => "rembrandt", :url_string => "http://rembrandt.com/test.jpg")
-      old_url_ids = ArtistUrl.order("id").pluck(&:id)
+      old_url_ids = ArtistURL.order("id").pluck(&:id)
       artist.url_string = "http://rembrandt.com/test.jpg"
       artist.save
-      assert_equal(old_url_ids, ArtistUrl.order("id").pluck(&:id))
+      assert_equal(old_url_ids, ArtistURL.order("id").pluck(&:id))
     end
 
     should "normalize urls before removing duplicates" do

test/unit/artist_url_test.rb

@@ -1,6 +1,6 @@
 require 'test_helper'
 
-class ArtistUrlTest < ActiveSupport::TestCase
+class ArtistURLTest < ActiveSupport::TestCase
   def assert_search_equals(results, conditions)
     assert_equal(results.map(&:id), subject.search(conditions).map(&:id))
   end
@@ -196,7 +196,7 @@ class ArtistUrlTest < ActiveSupport::TestCase
     end
 
     context "#search method" do
-      subject { ArtistUrl }
+      subject { ArtistURL }
 
       should "work" do
         @bkub = create(:artist, name: "bkub", is_deleted: false, url_string: "https://bkub.com")