fix retro_blog for newer version of external lib

Since 2010-04-30 acts-as-taggable-on uses namespaces for their
models. This patch is needed to run the retro_blog extension with recent
versions of acts-as-taggable-on.

This fixes http://retrospectiva.org/tickets/840

config/environment.rb

@@ -22,7 +22,7 @@
   # They can then be installed with "rake gems:install" on new installations.
   config.gem 'rack', :lib => 'rack', :version => '~> 1.0.0'
   config.gem 'will_paginate', :lib => 'will_paginate', :version => '>= 2.3.8'
-  config.gem 'acts-as-taggable-on', :lib => 'acts-as-taggable-on', :version => '>= 1.0.3' 
+  config.gem 'acts-as-taggable-on', :lib => 'acts-as-taggable-on', :version => '>= 2.0.4'
   config.gem 'RedCloth', :lib => 'redcloth', :version => '>= 4.1.9'
 
   # Only load the plugins named here, in the order given. By default, all plugins 

extensions/retro_blog/ext/project.rb

@@ -7,9 +7,9 @@
 
     def categories
       records = find :all,
-        :select => "DISTINCT #{Tag.quoted_table_name}.name",
+        :select => "DISTINCT #{ActsAsTaggableOn::Tag.quoted_table_name}.name",
         :joins => :categories,
-        :order => "#{Tag.quoted_table_name}.name"
+        :order => "#{ActsAsTaggableOn::Tag.quoted_table_name}.name"
       records.map(&:name) 
     end