Fix use of backend where it should say director.
Write changelog and do groundwork for 4.0.1-rc1.

We still have a few bugs left to fix, but start out with this so the
Jenkins machinery can be fine tuned in advance.
RST warnings in changes.rst is a hard error.
python-docutils v0.6 will have to do.

Seems like requiring a version from 2010 was way optimistic.

EL6 has v0.6 which was the first version rst2man appeared in.
Forgot to mention the 200 Not Modified fix.

Reminded by: daghf