Cleaned up TopicUserSpec, introduces clearing of pinned topics

db/migrate/20130306180148_add_cleared_pinned_to_topic_users.rb

@@ -0,0 +1,9 @@
+class AddClearedPinnedToTopicUsers < ActiveRecord::Migration
+  def change
+    add_column :topic_users, :cleared_pinned_at, :datetime, null: true
+
+    add_column :topics, :pinned_at, :datetime, null: true
+    execute "UPDATE topics SET pinned_at = created_at WHERE pinned"
+    remove_column :topics, :pinned
+  end
+end