Refresh exercise scripts

Change-Id: Ic97681c22e4ace6bf84dd3afc25161bc5d2cbae8
Merge branch 'cinder-backends' into dt-test
Merge branch 'add-pre-install' into dt-test
Merge branch 'reorder-stack.sh' into dt-test
Merge branch 'new-ceph-backend' into dt-test
Merge branch 'test-ca' into dt-test
Merge branch 'usb-prereq' 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