h3i: Test harness for recordreplay

[evanrittenhouse]

The h3i client currently doesn't have any tests to check parsing. We can set up an integration test harness that has qlog files which we test against - that way, we can ensure that there aren't any parsing regressions when we touch that code.

Bonus: We could also add some sort of README to the harness to make it easier for other contributors to add tests.