Modify lms acceptance test to use auto_auth.

lms/envs/acceptance.py

@@ -83,6 +83,9 @@ MITX_FEATURES['STUB_VIDEO_FOR_TESTING'] = True
 # per-test control for acceptance tests
 MITX_FEATURES['ENABLE_DISCUSSION_SERVICE'] = True
 
+# Use the auto_auth workflow for creating users and logging them in
+MITX_FEATURES['AUTOMATIC_AUTH_FOR_TESTING'] = True
+
 # Include the lettuce app for acceptance testing, including the 'harvest' django-admin command
 INSTALLED_APPS += ('lettuce.django',)
 LETTUCE_APPS = ('courseware',)