fix content type of the result

lib/renderer.rb

@@ -16,7 +16,7 @@ class Renderer
     type = get_preferred_type(session, template)
     type = template.first[0] if type == DEFAULT_TYPE
     session.response.body = Tilt.new(template[type]).render(session.options)
-    session.response.content_type = type
+    session.response.content_type = type_map[type]
     nil
   end
 
@@ -49,6 +49,10 @@ class Renderer
     }
   end
 
+  def self.type_map
+    @type_map ||= types.invert
+  end
+
   def self.get_preferred_type(session, template)
     session.request.accept.types.each do |type|
       next unless types.has_key? type