Verify token when configuring webhook from facebook dev.
        
        MessengerBot.id is used for verification

def get(self, request, hook_id):
        """
        Verify token when configuring webhook from facebook dev.
        
        MessengerBot.id is used for verification
        """
        try:
            bot = caching.get_or_set(MessengerBot, hook_id)
        except MessengerBot.DoesNotExist:
            logger.warning("Hook id %s not associated to a bot" % hook_id)
            return Response(status=status.HTTP_404_NOT_FOUND)
        if request.query_params.get('hub.verify_token') == str(bot.id):
            return Response(int(request.query_params.get('hub.challenge')))
        return Response('Error, wrong validation token')