Add more metrics

[hannesstruss]

• Number of buiilds per day
• Use median instead of avg. build time

[mobilekosmos]

Hello, do you have plans of improving this? I find it really helpful, or is there meanwhile another tool that is better?

[hannesstruss]

@tererecool I do have plans, although the first steps would probably be to replace the charting engine with something nicer, like Highcharts, and to get rid of all Groovy code. That said, pull requests are always welcome!

You can also check out https://github.com/passy/build-time-tracker-plugin , I haven't tried it myself, but looks like it does a similar job.