Ease the new-dev process and add a zephyrbot

This adds a zephyrbot, along with a couple changes to try to make setting up zscore easier for new (potential) developers. If it would be helpful, I can add some instructions on how you might run the zephyrbot in production, and I'm happy to do whatever it would take to start running this. (I have some experience with running zephyrbots from maintaining chiron...)