Implement configurable retry

[seako]

Ideally every integration test would work every time. But I'm sure we've all written or seen tests that work most of the time but sometimes need to be retried for them to work. It would be great if tests and steps had retry configuration that let you specify the number of times to retry them before they're regarded as failed.

[MykolaDudar]

Opportunities I see

1. Configure number of automatic re-tries for each test in the test suite
2. Give option to re-run tests that failed in the last run
3. Configure number of automatic re-tries for each test step in each test in the test suite

[wmatson]

Another possible option: some sort of middleware or fixture-like option for creating/adding new features from userspace easily