Get travis running successfully for python 3.x, django 1.7

[troygrosfield]

The issue with django 1.7 has to do with south and django's new migrations:

0.73s$ coverage run manage.py test $TESTS --settings=$SETTINGS -v2
Coverage.py warning: Module open_facebook was never imported.
Traceback (most recent call last):
  File "manage.py", line 11, in <module>
    execute_from_command_line(sys.argv)
  File "/home/travis/virtualenv/python3.4.1/lib/python3.4/site-packages/django/core/management/__init__.py", line 385, in execute_from_command_line
    utility.execute()
  File "/home/travis/virtualenv/python3.4.1/lib/python3.4/site-packages/django/core/management/__init__.py", line 354, in execute
    django.setup()
  File "/home/travis/virtualenv/python3.4.1/lib/python3.4/site-packages/django/__init__.py", line 21, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/home/travis/virtualenv/python3.4.1/lib/python3.4/site-packages/django/apps/registry.py", line 85, in populate
    app_config = AppConfig.create(entry)
  File "/home/travis/virtualenv/python3.4.1/lib/python3.4/site-packages/django/apps/config.py", line 87, in create
    module = import_module(entry)
  File "/home/travis/virtualenv/python3.4.1/lib/python3.4/importlib/__init__.py", line 109, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 2254, in _gcd_import
  File "<frozen importlib._bootstrap>", line 2237, in _find_and_load
  File "<frozen importlib._bootstrap>", line 2224, in _find_and_load_unlocked
ImportError: No module named 'south'
The command "coverage run manage.py test $TESTS --settings=$SETTINGS -v2" exited with 1.

This was from the following test failure:

• https://travis-ci.org/tschellenbach/Django-facebook/jobs/38684865

For references to fixes, see:

• https://docs.djangoproject.com/en/dev/topics/migrations/#libraries-third-party-apps
• http://south.readthedocs.org/en/latest/releasenotes/1.0.html#library-migration-path

Ping: #493, #491