Backport of fix for 24-hour failure of pki.

A 401 from the admin token was being treated as an invalid user token
and the admin token was never re-requested. This would cause all
services to incorrectly report all tokens as invalid after the service
had been running for 24 hours. This change re-requests the admin token
and attempts to revalidate instead of returning 401.

Original commit message follows:

fixes bug 1074172

updated diablo token based on output from diablo/stable keystone
added expiry to example tokens for test_auth_middleware
added a stack based HTTP response to test_auth_middleware to verify
sequencing

Change-Id: I738b0e9c1a0e62ad86adb95ec0b73f621513f7d4
(cherry picked from commit 7cc02c80cfb1976271fa8b6271091fcd35c1cb34)