Move design_doc_* attributes into DesignDoc mixin

lib/couchrest/mixins/design_doc.rb

@@ -9,6 +9,12 @@ module CouchRest
       end
       
       module ClassMethods
+        attr_accessor :design_doc, :design_doc_slug_cache, :design_doc_fresh
+        
+        def design_doc
+          @design_doc ||= Design.new(default_design_doc)
+        end
+        
         def design_doc_id
           "_design/#{design_doc_slug}"
         end

lib/couchrest/mixins/views.rb

@@ -7,12 +7,6 @@ module CouchRest
       end
       
       module ClassMethods
-        attr_accessor :design_doc, :design_doc_slug_cache, :design_doc_fresh
-        
-        def design_doc
-          @design_doc ||= Design.new(default_design_doc)
-        end
-        
         # Define a CouchDB view. The name of the view will be the concatenation
         # of <tt>by</tt> and the keys joined by <tt>_and_</tt>
         #