Review waiting on...
A perennially popular question is "who is this review waiting on?" aka "why can't I merge already?!" Reviewable now gives you an answer:
Note that the list may not be complete or precise; e.g., in a new, unassigned review, there's no way to tell who you're waiting for, and in multi-party reviews one person taking action may render another person's participation moot. Still, it should give you a pretty good idea who to nag!
The list is also included in the pull request's code-review/reviewable status, which I've shortened to fit as much information as possible into the 50 (!) character limit.
Both the pending reviewers and short description properties can also be filled out by custom completion conditions. I've updated the examples to show you how they work, and also took this opportunity to bump the execution environment to NodeJS 4.3.x for some modern JavaScript action. Enjoy!