Add little success rate chart to metrics tables

Add a small success rate chart to the Metrics tables:

![screen shot 2018-09-05 at 3 10 50 pm](https://user-images.githubusercontent.com/549258/45124297-9a42bb80-b11e-11e8-8a42-74cffdd05797.png)
