Cool tool! I run a GitHub code review app myself (
https://reviewable.io) and have a similar feature built-in to customize the completion condition:
https://github.com/Reviewable/Reviewable/wiki/FAQ#can-i-cust.... The main difference is that you took a declarative approach, which I contemplated but discarded after checking with my users and discovering how much variety there was in their approval algorithms. I'm running user scripts on AWS Lambda instead:
http://blog.reviewable.io/your-code-my-app-no-worries.
I'll be curious to see how your project works out!