bootspeed charts should show LTS baseline

[Dimitri John Ledkov]

Currently looking at http://reports.qa.ubuntu.com/bootspeed/machine/1/amd64/ there is a horizontal line that displays raring release image values. It acts as a visual baseline. Using raring is useful, but not much, since the bootspeed results are available from way before raring release.

Ideally the horizontal line should be for the last LTS (currently precise) as LTS -> LTS regressions/improvements are the most important ones. (E.g. a 2 second improvement since raring is not good, if it's still an overall 10 second regression from precise).

ps. I'm not sure if it should be precise-daily or .0 release, or multiple "baselines" for each point release given that they are significantly different with the hwe stacks. Maybe just the best one out of .0, .1, .2 and precise-daily as we want to be even better.

[Gema Gomez (gema)]

Maybe it would make sense to have a different graph for the released images, a higher level trend graph if you like that would show how well we are doing from release to release. We could have this to show either at the front of each graph, just to be able to see the changes or a different graph.

As per conversation with xnox, maybe the horizontal bar should be a "best ever result" rather than the last released image.