RCv3 positive integration tests

Closes #840.
To be clear: `setFormatter` prior to log file generation is what we want (assuming it doesn't break Jenkins), right? IIUC the weird in-memory collection stuff happens in a handler which consumes `LogRecord` objects, so it should work fine with setting the formatter.

As for breaking Jenkins or not: I'd assume that these logs are primarily for human consumption, so if that breaks Jenkins, it's really a bug in Jenkins?