Fix deprecated urls import.
Make travis build python 3.3 and django 1.6 beta.

...and turn off CI email notifications.
Fix django 1.6 import error.

As suggested in https://github.com/KristianOellegaard/django-hvad/issues/116
Fix expectation of number of queries in django 1.6.
Fix select related for django 1.6.

The signature of django.db.models.sql.query.Query.join
changed in django 1.6 because of https://code.djangoproject.com/ticket/19385
Fix use of multiple context managers.