Set default for LOGDIR

Change-Id: I1fca16fa4e857c624c5b1fb1bc87df774ff92520
Merge branch 'rename-screen-logs' into dt-test
Merge branch 'screen-logdir-again' into dt-test
Merge branch 'nonovnc' into dt-test
Merge branch 'identity-v3-default' into dt-test
Merge branch 'conf-tempest' into dt-test
Merge branch 'test-service-functions' into dt-test
Merge branch 'exercise-refresh' into dt-test