is_revoked check all viable subtrees

An indentation error coupled with an early return lead to cases
where a subtree containing a pertinent revocation event was not
searched, and a revoked token would report as unrevoked.

Closes-bug: #1294292
Change-Id: If56ae64d8a30b461563ee8be002544117fb14215
Add support for parallel testr workers in Keystone

Full support for parallel testr workers now works in keystone. The
major item to be aware of is that if non-SQLite backends or a LIVE
LDAP backend is being used for testing, the concurrency must be set
to 1 to avoid conflicts. To artificially set the concurrency set
the env variable ``TEST_RUN_CONCURRENCY`` to the desired number of
testr workers. The default is to run one worker. To use 1 per
available core, set ``TEST_RUN_CONCURRENCY`` to 0.

Each worker uses a subdirectory of the test temp dir  based upon
the PID. When the worker exists (via the use of atexit), the
worker-specific PID directory is automatically removed.

The first time concurrent tests are run in a given environment,
ensure that old .testrepository directories are cleaned up as they
may introduce bad learning data on how to bin the tests based upon
test runs that occured without concurrency.

Closes-Bug: #1240052
Change-Id: I5c3385a431774ce574266a82065ed6237e8b3665
Merge "is_revoked check all viable subtrees"