Explain how to set a date header like Expires

```
Could you please extend the docs to explain how to set a date header like 
Expires?

Should it be done via custom processor? Couldn't find supporting code to do it 
out of the box.

Regards.


```

Original issue reported on code.google.com by `spranger...@googlemail.com` on 1 Oct 2013 at 10:41
