Work on Python 2.6

[msabramo]

by using unittest2 so skipUnless is available.

$ tox -e py26
py26 create: /Users/marca/dev/git-repos/django_ci_example/.tox/py26
py26 installdeps: -rrequirements.txt
py26 runtests: PYTHONHASHSEED='761356824'
py26 runtests: commands[0] | python manage.py test
nosetests --verbosity=1
Creating test database for alias 'default'...
S..........
----------------------------------------------------------------------
Ran 11 tests in 0.086s

OK (SKIP=1)
Destroying test database for alias 'default'...
_________________________________________________________________________________________________________________________________________________________ summary __________________________________________________________________________________________________________________________________________________________
  py26: commands succeeded
  congratulations :)