Adaptation to Gitlab 10.2 tokens management

Personal tokens are now in a dedicated page. The main difference for these automated tests is that they can't be re-read. The only possibility is to create a token, and read it right after creation.

Later on, we'll consider caching them in a local file, but for now this is good enough to make our tests pass for Heptapod rebased on top of Gitlab 10.2.8