Implement docker hub webhook to jenkins

[peschmae]

Since we already have a automated build pipeline for our docker images, it would be great to have continuous deployment as well.

Documentation on Docker Hub Webhooks
https://docs.docker.com/docker-hub/webhooks/

Jenkins Plugin for Docker Webhooks: https://wiki.jenkins.io/display/JENKINS/CloudBees+Docker+Hub+Notification
http://www.tothenew.com/blog/automated-docker-deployment-using-jenkins/

[peschmae]

Path that needs to be accessible, either with a service user, or without credentials: /dockerhub-webhook/notify

[peschmae]

The develop project is already configured that it should work, as soon as docker-hub is able to post to the aforementioned URL