Java selenium test

Please review the changes for blackbox integration testing for Fronts. This is a new module so check out the [README](https://github.com/guardian/frontend/blob/java-selenium-test/integration-tests/java-selenium/readme.md) file under <root>/integration-test/java-selenium. It contains a description and how to run the tests locally.
Can you update this file, so that `Fronts testing overview.png` reflects the current testing approach? Ie. the prod-based testing