Fixed the policy tests in Python 3

The file builtin was removed in Python 3. open should be used instead.

bp python3

Change-Id: Ib394b9ceeffb1ae8fd4cbebbd0818c64e24e55e6
Adds several more tests to the Python 3 test run

bp python3

Change-Id: Idd1e60dff813a65898ce6a53d21a8d06fae2bdfe