Fix ACI conversion and add a registry test for it

test/registry/protocol_fixtures.py

@@ -33,7 +33,7 @@ def sized_images():
     Image(id='parentid', bytes=parent_bytes, parent_id=None, size=len(parent_bytes),
           config={'foo': 'bar'}),
     Image(id='someid', bytes=image_bytes, parent_id='parentid', size=len(image_bytes),
-          config={'foo': 'childbar'}),
+          config={'foo': 'childbar', 'Entrypoint': ['hello']}),
   ]