fix: don't crash when saving a product in the admin interface

cash/models.py

@@ -9,7 +9,7 @@ from django_auth_ldap.backend import populate_user
 from django.utils.translation import ugettext_lazy as _
 from django.utils.translation import ugettext_noop
 from django.db import transaction
-import PIL
+import PIL.Image
 import StringIO
 
 class Account(models.Model):