Report if there are any errors in local_settings.

This will issue a `UserWarning` in case some kind of exception is being
raised inside local_settings.py

settings.py

@@ -149,5 +149,9 @@ INBOUND_EMAIL_VALIDATION_KEY = 'totally-unsecure-validation-string'
 # If you have settings you want to overload, put them in a local_settings.py.
 try:
     from local_settings import *  # noqa
-except ImportError:
-    pass
+except ImportError as exc:
+    import warnings
+    import traceback
+
+    warnings.warn('Could not import local_settings module. {}'.format(
+        traceback.format_exc()))