trends view updates and improvements

[trey-ivy]

The current trends view is basically worthless and i think we are to the point now where adding some basic trending data can take priority. I would like to implement a nightly (or scheduled on a user defined frequency) job that calculates the following:

• longest running targets and tests (max and avg durations)
• most often built targets (not served from local cache or remote cache)
• targets most often served from cache (local and remote)
• most often executed tests (not cached)
• most often failed targets and tests
• average time per build step (CI stage)
• most often failed build step
• most often failed worker

And anything else we can think of as we go along. In the beginning, just having the top 10-20 of these entries in a tabular view with relevant links will be awesome. Further down the rode, maybe we can add some graphs where it makes sense.