Fix reply-to header problem

I think release ``2.0.8`` is completely broken, because the reply-to header is set incorrectly.
We have no integration test for catching this error and it is currently hard to write one because we only have a javascript implementation.

Changes:
- Correctly encode reply-to header (``actor``).
- Add missing changelog entry from refactoring in ``2.0.8``
- Mark ``2.0.8`` has broken in changelog.

@maethu