Meant to be useful to chromium developers (for buildbot and/or codereview).
Adds some useful information in polygerrit/rietveld and buildbot UIs.
* Shows which file has been LGTMed by owners, which files are missing owner reviews etc.
* Suggests a list of reviewers for files that still don't have an owner as a reviewer.
* Allow adding OWNERS to the reviewer list.
* Shows the blame-list, and the list of failures for a particular bot.
* Links to the changed files from for a particular run in a buildbot.