Add explicit User < ActiveRecord::Base definition to migration 009 so that it will work for a user upgrading from r280 to trunk. John Athayde reported this problem on the mailing list.

git-svn-id: http://www.rousette.org.uk/svn/tracks-repos/trunk@336 a4c988fc-2ded-0310-b66e-134b36920a42

tracks/db/migrate/009_add_user_pref_refresh.rb

@@ -1,4 +1,7 @@
 class AddUserPrefRefresh < ActiveRecord::Migration
+  
+  class User < ActiveRecord::Base; serialize :preferences; end
+  
   def self.up
     @users = User.find(:all)
     @users.each do |user|