xRetry only reports output from final retry

[jchesshirAspire]

The xRetry architecture appears to only be reporting the output from the final retry of a test, which can be hindering when trying to diagnose the root cause of a failure.

Even though test runs should, theoretically, be atomic in their execution, there are inevitably going to be times (especially when performing integration testing) when a retry will stumble because of a condition left around by the initial test run or one of the previous retries. Because of this, it can be very helpful to have the output from all of the test failures sent to the logs, not just the output from the last retry.

Now it would be good to have all of this output sent to the logs at once so that the person trying to diagnose the issue doesn't have to search for the output from the previous runs. It would also be good to have this data in the XML output file all under the results of the same test. But even if the data was scattered throughout the log file, it would be better than nothing at all.

[JoshKeegan]

Similar to #242 - maybe they could be combined.

I like the idea of including the test output for every attempt, although I expect most projects would want to keep the current behaviour of just reporting the last attempt so this should be configurable. I never got around to implementing config though (#77) so that should come first.