Artist urls can be prepended with a '-' to mark is inactive (#3388)

db/migrate/20180516222413_add_is_active_to_artist_urls.rb

@@ -0,0 +1,7 @@
+class AddIsActiveToArtistUrls < ActiveRecord::Migration[5.2]
+  def change
+    ApplicationRecord.without_timeout do
+      add_column :artist_urls, :is_active, :boolean, null: false, default: true
+    end
+  end
+end