Add logging.

model_logging/migrations/0001_initial.py

@@ -2,6 +2,7 @@
 from __future__ import unicode_literals
 from django.db import models, migrations
 from unittest.mock import Mock
+import logging
 
 """
 The assumption is that a user who is upgrading from 0.1.0 to this version will already have pgcrypto installed. We also check this in 0003 so that they have a verbose error message.
@@ -11,6 +12,7 @@
 try:
     import pgcrypto.fields
 except ImportError:
+    logging.warning('Since pgcrypto is not installed. We are now mocking it.')
     pgcrypto = Mock()
 
 from django.conf import settings