Implement isLeaf spec.
Start specifying argument parsing and logging behavior.
Specify that twisted logging should be piped into stdlib logging.
Implement current arg parsing / logging config spec.
Update spec and impl to separate argument parsing (which does no IO now) and log initialization.
Change a bad secret to an easier one to type.
Improve mockutil a bit, fix a typo therein, and add a spec&impl for LogMixin.
Move log mocking into a reusable test base class in anticipation of reuse in other specs.
Prepare for WebhookResource to be a LogMixin.