Tidy up initialisations of design_doc which are no longer needed

lib/couchrest/mixins/design_doc.rb

@@ -16,7 +16,6 @@ module CouchRest
         def design_doc_slug
           return design_doc_slug_cache if (design_doc_slug_cache && design_doc_fresh)
           funcs = []
-          self.design_doc ||= Design.new(default_design_doc)
           design_doc['views'].each do |name, view|
             funcs << "#{name}/#{view['map']}#{view['reduce']}"
           end

lib/couchrest/mixins/document_queries.rb

@@ -12,7 +12,6 @@ module CouchRest
         # name of the current class. Take the standard set of
         # CouchRest::Database#view options.
         def all(opts = {}, &block)
-          self.design_doc ||= Design.new(default_design_doc)
           unless design_doc_fresh
             refresh_design_doc
           end