Merge branch 'master', remote-tracking branch 'upstream/master'

Conflicts:
	guardian/admin.py
	guardian/core.py
	guardian/managers.py
	guardian/models.py
	guardian/shortcuts.py
	guardian/tests/__init__.py
	guardian/tests/admin_test.py
	guardian/tests/testapp/models.py
	guardian/tests/utils_test.py
Fixes from merge and updates for tests