detect and report outliers (#6)

[candrewlee14]

Resolves #6

Also fixes the median statistic, which I believe was taking the middle item of an unsorted list of samples (instead of sorted).

[andrewrk]

looks great.

btw why sudo being used here?

[candrewlee14]

When I don't run with sudo, I get this error: thread 918174 panic: unable to open perf event: PermissionDenied

[andrewrk]

aha, that's interesting. you should be able to run a simple command to toggle the setting and allow users to view perf events without root. I filed this related issue: #17