Merge branch '15-single-sign-off' into 'master'

.gitlab-ci.yml

docker-compose.yml

logout_provider/Dockerfile

logout_provider/app.py

logout_provider/requirements.txt

test/create-hydra-client.bash

test/integration_tests/Dockerfile

test/integration_tests/README.md

test/integration_tests/app.py

test/integration_tests/requirements.txt

test/integration_tests/test/behave/features/environment.py

test/integration_tests/test/behave/features/logout.feature

...s/test/behave/features/reject_unauthorized_logins.feature