Writes a hunt object to the database.

def WriteHuntObject(self, hunt_obj):
    """Writes a hunt object to the database."""
    if hunt_obj.hunt_id in self.hunts:
      raise db.DuplicatedHuntError(hunt_id=hunt_obj.hunt_id)

    clone = self._DeepCopy(hunt_obj)
    clone.create_time = rdfvalue.RDFDatetime.Now()
    clone.last_update_time = rdfvalue.RDFDatetime.Now()
    self.hunts[(hunt_obj.hunt_id)] = clone