refactor factories and add #show tests for posts controller

Do not want to cache classes, but do want to reload models after factory girl:

http://groups.google.com/group/factory_girl/browse_thread/thread/daa24556d90c31fc
http://stackoverflow.com/questions/5145165/associationtypemismatch-and-factorygirl

rails_autolink was removed from Rails 3.1 and abstracted to an external gem
fix display author name and post time on comment show
fix namespace for thanking and moderated flash notices

lib/refinery/blog/engine.rb

@@ -1,6 +1,8 @@
 module Refinery
   module Blog
     class Engine < Rails::Engine
+      require 'rails_autolink'
+      
       config.to_prepare do
         require 'refinery/blog/tabs'
       end