benchmarks: Report more metrics (min/max/median)

benchmarks: Report more metrics (min/max/median)

Add minimum, maximum, median to the report in addition to the mean (average)
which was already there. Based on benchmarkTidy.php from I254793fc5.

Example output:

> Delete
>    times: 10
>    total:   7.47ms
>      min:   0.53ms
>   median:   0.74ms
>     mean:   0.75ms
>      max:   1.21ms
>
> Truncate
>    times: 10
>    total:  72.38ms
>      min:   1.37ms
>   median:   8.32ms
>     mean:   7.24ms
>      max:  15.73ms

Change-Id: Ifd3064a3621e07f55505490403189cb47022c6c7