add tests for CREATE_UNKNOWN_USER setting; also make all tests django TestCase instances
add tests for CREATE_UNKNOWN_USER setting; also make all tests django TestCase instances

Brown-University-Library/django-shibboleth-remoteuser,uchicago-library/django-shibboleth-remoteuser,trevoriancox/django-shibboleth-remoteuser,Brown-University-Library/django-shibboleth-remoteuser,trevoriancox/django-shibboleth-remoteuser,uchicago-library/django-shibboleth-remoteuser