Add nose34 test for pywikibot and Python 3

Make use of the recent '{name}-tox-{toxenv}-trusty' job template
introduced by: https://gerrit.wikimedia.org/r/#/c/164065/

Signed-off-by: Antoine Musso <hashar@free.fr>
Change-Id: I5da4e5e7311194345a4e44b011f0e2eed6613ae1