Just use the vanilla mime type string, no need for fancy lookups [DHH]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@5154 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

actionpack/lib/action_controller/mime_responds.rb

@@ -130,12 +130,12 @@ def custom(mime_type, &block)
         
         if block_given?
           @responses[mime_type] = Proc.new do
-            eval "response.content_type = Mime::#{mime_type.to_sym.to_s.upcase}", @block_binding
+            eval "response.content_type = '#{mime_type.to_s}'", @block_binding
             block.call
           end
         else
           if source = DEFAULT_BLOCKS[mime_type.to_sym]
-            @responses[mime_type] = eval(source, @block_binding)            
+            @responses[mime_type] = eval(source, @block_binding)
           else
             raise ActionController::RenderError, "Expected a block but none was given for custom mime handler #{mime_type}"
           end