.stop() followed directly by .reset() doesn't work. It seems asio has a
"can run" boolean variable, stop sets it to false, reset to true, so if
they are both called from inside the .run() main loop, it does nothing.

* Wrapped long lines, whitespace fixes
* Some spelling
* Test port in the private range

[trac678] refactor the stop interface for udp and tcp server and related unittest to dns_server_unitttest

Listen on the IPv6 (::) and IPv4 (0.0.0.0) wildcard addresses
for b10-auth. This returns to previous behavior prior to
change #184. Document the listen_on configuration in manual.
(Trac #649)

Conflicts:
tests/system/{cleanall.sh, conf.sh.in, ifconfig.sh, run.sh, runall.sh}
These were actually re-added to the tree.

For distcheck we only needed cleanall.sh, but to make tar balls complete
we need other files including test scripts and data.

Some other cleanups are piggy-backed:
- use port 53210 instead of 5300 to be aligned with trac #523
- use reference to BIND 9 tools (instead of copying them) when we don't
  need to modify them

but the original test code was wrong and didn't make sense.

as suggested in review.

Fixed some style issues, made the singleton instance a static object, and added a bit of documentation

skipping review.