QA regression test (QRT) suite integration

[aquette]

Integrate the QRT work done for Ubuntu in NUT mainline.
Quoting docs/nut-qa.txt:

a runtime testing suite, which automates the inter layer communication testing
(driver - upsd - upsmon / clients), that is part of Ubuntu.
The NUT testing script is available in the Ubuntu QA Regression Testing suite:

• http://bazaar.launchpad.net/~ubuntu-bugcontrol/qa-regression-testing/master/view/head:/scripts/test-nut.py => https://git.launchpad.net/ubuntu/+source/nut/tree/debian/tests
• https://code.edge.launchpad.net/qa-regression-testing.

It installs nut, configure with for the dummy-ups driver, changes a few data and
check that these are well propagated with upsc.

This probably involves testlib.py, but should be limited if it goes beyond!

NOTE: it's a good time to reconsider QRT as a whole!
Other framework may now be more suitable to test our broader scope (OS at least)

Also hook it to the "check" target, for buildbot use.