Merge pull request #306 from singlerider/fix-mongodbengine-check

fix mongodb engine check

Author: macro1

AUTHORS.rst

@@ -42,6 +42,7 @@ Authors
 - Gregory Bataille
 - Jesse Shapiro
 - Kevin Foster
+- Shane Engelman
 
 Background
 ==========

simple_history/models.py

@@ -321,7 +321,7 @@ def convert_auto_field(field):
     must be replaced with an IntegerField.
     """
     connection = router.db_for_write(field.model)
-    if settings.DATABASES[connection]['ENGINE'] in ('django_mongodb_engine',):
+    if settings.DATABASES[connection].get('ENGINE') in ('django_mongodb_engine',):
         # Check if AutoField is string for django-non-rel support
         return models.TextField
     return models.IntegerField