fixes #858

adds color coding to both urls and other names on artist versions

app/helpers/artist_versions_helper.rb

@@ -1,2 +1,31 @@
 module ArtistVersionsHelper
+  def artist_version_other_names_diff(artist_version)
+    diff = artist_version.other_names_diff(artist_version.previous)
+    html = []
+    diff[:added_names].each do |name|
+      html << '<ins>' + name + '</ins>'
+    end
+    diff[:removed_names].each do |name|
+      html << '<del>' + name + '</del>'
+    end
+    diff[:unchanged_names].each do |name|
+      html << '<span>' + name + '</span>'
+    end
+    return html.join(" ").html_safe
+  end
+
+  def artist_version_urls_diff(artist_version)
+    diff = artist_version.urls_diff(artist_version.previous)
+    html = []
+    diff[:added_urls].each do |url|
+      html << '<li><ins>' + url + '</ins></li>'
+    end
+    diff[:removed_urls].each do |url|
+      html << '<li><del>' + url + '</del></li>'
+    end
+    diff[:unchanged_urls].each do |url|
+      html << '<li><span>' + url + '</span></li>'
+    end
+    return html.join(" ").html_safe
+  end
 end