Let Kong Adapter, Mailer, Chatbot check for changed configuration

[DonMartin76]

In order to gain more flexibility and safety during updates of both configuration and images, the following behavior of components depending on the Portal API may be very helpful:

• The portal API provides and end point which gives back some kind of hash of the static configuration
• When calling webhooks, this hash is passed in as a header parameter (Configuration-Hash or similar)
• At startup, each component retrieves the initial hash and stores it in memory
• Whenever a hash mismatch is detected, e.g. because the portal API has restarted and retrieved/gotten a new configuration, the depending component can take action
• Such an action could be just to quit the current process to let the orchestration layer (e.g. compose or Kubernetes) restart the container, so that the new configuration can be retrieved from the portal API

This would enable a much easier handling of configuration updates: It would be enough to stop/restart the portal API, and all other components would automatically draw the new configuration. Such behavior would be ideal for environments such as Kubernetes.