Custom anonymous user username.

The first anonymous user created needs a configurable value
since django 1.5 supports custom user modules.
Django 1.5 foreign key dependency

Also make sure that code doesn't call compat.py twice.
This ensures there's no circular dependencies.
Merge remote-tracking branch 'abec/master'

Conflicts:
	guardian/compat.py
	guardian/models.py
	guardian/utils.py
Merge pull request #1 from fhahn/master

Updated your patch for AnonymousUser creation in Django 1.5
Merge pull request #110 from abec/master

AnonymousUser creation in Django 1.5