Tests cleanup temporary files

Some tests in test_auth_token_middleware weren't cleaning up
temporary files because the original filename was lost when
set_middleware() was called twice or tearDown() didn't clean up
the files.

The fix strategy is to use cleanUp(), because it will delete all
files even if called multiple times, and it doesn't rely on
tearDown() being called in subclasses.

Change-Id: Ib78150378ba6b622c9bc451ef4b331a87c17c56a
auth_token tests close temp file descriptor

The auth_token middleware tests were failing to close the
file descriptor of the named temporary file.

The fix strategy is to use tempfile.NamedTemporaryFile in a
context manager rather than mkstemp.

Change-Id: Ie20e2b4faa6a0d6bb8c4817ed2c9a04adee96f0f
Clarify roles validation error messages

When doing the xor validation tests, we should differentiate between
the case where the user passed both arguments vs passing neither,
otherwise the error message is confusing when you don't pass either.

Change-Id: I99c307339ccd045a4c5b71824f3b7d91e2908154
Merge "Clarify roles validation error messages"
Merge "Tests cleanup temporary files"
Merge "auth_token tests close temp file descriptor"