This adds UI to

- display the status of HEAD
- select commit ranges
- better listing of tests that need triaging.

Next CL adds the backend to animate these.

BUG=skia:2930

Review URL: https://codereview.chromium.org/794903003
Add links to monit and logserver endpoints for each server.

BUG=skia:

Review URL: https://codereview.chromium.org/801893002