update-payload-extractor: Import master update_payload

Change-Id: I94798f08b2e02677390024abcd43d45af7f585ee

update-payload-extractor/update_payload/__init__.py

@@ -17,6 +17,8 @@
 """Library for processing, verifying and applying Chrome OS update payloads."""
 
 # Just raise the interface classes to the root namespace.
+from __future__ import absolute_import
+
 from update_payload.checker import CHECKS_TO_DISABLE
 from update_payload.error import PayloadError
 from update_payload.payload import Payload