code: def json(self, dict=None, indent=None):
          
          if not dict:
              dict = self.dict()
          for key, value in dict.iteritems():
              if type(value) == datetime.datetime:
                  dict[key] = value.strftime(conf.GOSCALE_ATOM_DATETIME_FORMAT)
          return simplejson.dumps(dict, indent=indent)
docs: Returns post JSON representation