Import order is fixed

In keystone/tests/fakeldap.py built-in lib import was among third party
libs imports.

Change-Id: I94d5dc54b94193c2da2509589402b738daa4b575
Remove unnecessary calls to self.config()

tests.TestCase:setUp calls self.config(), so there's no need to call
it again.

Change-Id: I02d460d5b0fa7b885f1134198c3215bc69649461
Call an existing method in sync cache for revoke events

The cache used for synchronizing the revocation tree across
green threads had an issue where it was calling a non-existant
method ``remove`` instead of ``remove_event``. The correct method
is now being called and an expanded test to exercise the synchronize
method has been added.

Change-Id: I3fe47fa51f88aab89480831b2d95746319f82ceb
Closes-Bug: 1289935
Merge "Call an existing method in sync cache for revoke events"
Merge "Remove unnecessary calls to self.config()"
Merge "Import order is fixed"