Return creation date

        :rtype: datetime
        :raises ResourceNotFound: resource not found on the API

def created(self):
        """Return creation date

        :rtype: datetime
        :raises ResourceNotFound: resource not found on the API
        """
        if 'id_perms' not in self:
            self.fetch()
        created = self['id_perms']['created']
        return datetime.strptime(created, '%Y-%m-%dT%H:%M:%S.%f')