PERF: finalize porting to new incoming links structure

db/migrate/20140804030041_remove_url_from_incoming_referer.rb

@@ -0,0 +1,9 @@
+class RemoveUrlFromIncomingReferer < ActiveRecord::Migration
+  def up
+    remove_column :incoming_referers, :url
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end