Sanitize option defaults in autogenerated config reference

This fixes a number of glitches in the default option values shown
in the docs, many of which involve exposing information about the
system where the docs were built. In particular:

* The hostname and IP address are changed to neutral defaults.
* Python's site-packages location is changed to a neutral default.
* Values where whitespace is significant are quoted, as they are
  in the sample config files.

Change-Id: Ie3dafd53d0b8c49998ed513c44c7d133c8eb90c5