Analytics for merge rates

[johnynek]

A really interesting idea would be to build daily pages that show the merge rates for each version that is being bumped as well as CI pass-rate. It would very useful for library authors to see if they have pushed a version that breaks many downstream people.

Currently, library authors don't have an easy time quantifying the cost of breaks. By seeing the metrics on CI pass rate and merge rate, this might help us get a better handle on how many projects are hit by issues as we evolve libraries.