Revert "Merge "Avoid returning stale token via auth_token property""

This reverts commit b89d28663ed181e1df56ada271931891a4c77f67, reversing
changes made to 8a0732e262cd9de508399eabeb705b681c2503c0.

This change was causing gate issues. It breaks a few Keystone tests in
test_keystoneclient.py.

Change-Id: I8de6988c554a1359c04ce2d1a8c4707dee7c3782