How to add custom headers to webhook

Thanks @arakwar for your suggestion, that sound pretty reasonable. Adding a hook to the process is no problem. However, adding headers directly in the form for CAE might also be a worthwhile idea. If one doesn't require extra headers, they can just be left empty.

There is now an extra textarea in the configuration of this module which allows to provide header values in yaml format. Please give it a try and lets u know if that works, setting the issue to RTBC when appropriate.