fixed an inheritance problem with ExtendedDocument subclasses

lib/couchrest/mixins/design_doc.rb

@@ -6,9 +6,6 @@ module CouchRest
       
       def self.included(base)
         base.extend(ClassMethods)
-        base.send(:extlib_inheritable_accessor, :design_doc)
-        base.send(:extlib_inheritable_accessor, :design_doc_slug_cache)
-        base.send(:extlib_inheritable_accessor, :design_doc_fresh)
       end
       
       module ClassMethods

lib/couchrest/mixins/properties.rb

@@ -9,7 +9,7 @@ module CouchRest
       
       def self.included(base)
         base.class_eval <<-EOS, __FILE__, __LINE__
-            extlib_inheritable_accessor(:properties)
+            extlib_inheritable_accessor(:properties) unless self.respond_to?(:properties)
             self.properties ||= []
         EOS
         base.extend(ClassMethods)