REST attachment download Accept header types

[maierthomas]

In the REST attachment download endpoint it is necessary to set the Accept header, otherwise you will receive the following message:
"message": "Could not find acceptable representation",

So I tried to set the Accept header to */*
Result: "message": "Could not find acceptable representation",

Also images/* for the binary image is not working
Result: "message": "Could not find acceptable representation",

If you set the Accept header to application/* everything is working fine.
I could download the XML and a jpg image attachment successfully.

reference #769