CORD-1010 Fix Controller, Image, Network, and User model_policies

Change-Id: I42f8771048090666acd9d75ca32b6081a72ce880
diff --git a/xos/synchronizer/model_policies/model_policy_Image.py b/xos/synchronizer/model_policies/model_policy_Image.py
index 7e1a6f3..153b6b3 100644
--- a/xos/synchronizer/model_policies/model_policy_Image.py
+++ b/xos/synchronizer/model_policies/model_policy_Image.py
@@ -6,11 +6,12 @@
         return
 
     controller_images = ControllerImages.objects.filter(image_id=image.id)
-    existing_controllers = [cs.controller for cs in controller_images] 
-    
-    all_controllers = Controller.objects.all() 
+    existing_controllers = [cs.controller for cs in controller_images]
+    existing_controller_ids = [c.id for c in existing_controllers]
+
+    all_controllers = Controller.objects.all()
     for controller in all_controllers:
-        if controller not in existing_controllers:
+        if controller.id not in existing_controller_ids:
             sd = ControllerImages(image=image, controller=controller)
             sd.save()