Add Integration sample with Nuxeo Stream and Kafka

Hello,
 
As an FYI, in the context of IronMountain, I put together a sample code for integrating Nuxeo with an external service using Kafka.
 
The sample code is in https://github.com/nuxeo-sandbox/nuxeo-external-service-sample and it should contain:
 
 - some documentation
 - end to end unit tests
 
It can be seen as an illustration for a particular use case in https://gist.github.com/tiry/969d0d78393615edf5067b73543a2fce
 
If there is any interest, happy to discuss and see if we need to add/improve things.
 
Tiry