Initial commit of document source transformations

apps/sources/managers.py

@@ -0,0 +1,8 @@
+from django.db import models
+from django.contrib.contenttypes.models import ContentType
+
+
+class SourceTransformationManager(models.Manager):
+    def get_for_object(self, obj):
+        ct = ContentType.objects.get_for_model(obj)
+        return self.model.objects.filter(content_type=ct).filter(object_id=obj.pk)