Fixes#2448. Forward slash is no longer appended to the URL. If a user wants a / at the end of the URL, they will have to enter it in the webhook baseUrl.
* Access-Token Header is not sent if it has not been configured (or left blank)
* Access token is now also sent in URI string with "token" as key
* NotificationType is manually added to the notification data (original data is cloned before to avoid conflict in case of re-usage by other notification handlers)
