Switch e2e tests to use ginkgo

[munnerz]

By writing our e2e tests in Go, we develop far more intricate tests. We should look to rewrite our existing e2e tests into the same format, and from there look at writing more tests.

[wallrj]

I'm coming round to the idea.

I found that there are already some E2E tests for the Kubernetes examples, including Cassandra tests:

• https://github.com/kubernetes/kubernetes/blob/v1.8.4/test/e2e/examples.go#L226
• Introduced in https://github.com/kubernetes/kubernetes/pull/11044 ....but
• later deleted in https://github.com/kubernetes/test-infra/pull/3799, for consistent flakiness.

Perhaps we can get those tests working again with Navigator.