Fix test broken by 95aa2a9 (change form built-in logging to logging module)
Rename TestAuthRequestMixin so that nose doesn't collect it as a test.

Nose is apparently quite aggressive about what it considers to be a test.
TestAuthRequestMixin was being treated as a test (even though it does not
inherit from unittest.TestCase) solely on account of its name.
Merge pull request #64 from dairiki/tests

Fixes for failing tests