Clean up TLS CA functions

Fix cert file locations and clean up some naming

Change-Id: Ifc05b52a3a2eb119d402a3fd3ff1ab545ae9a6c7
Merge branch 'tls-update' 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