Updated your patch for AnonymousUser creation in Django 1.5

I've updated your patch (#110)  to work with the latest master of django-guardian.
There were some merge conflicts because of some other changes concerning Django's custom user model.

Are you still working on the patch or should I create a new pull request for the official django-guardian repo?

At the moment a lot of tests fail for a project with a custom user without username, because of the user creation during the tests. I'll look into that.