initial work in progress to add PerfUtil support to Fuchu

Don't merge yet, WIP. Comments welcome.

End result aim: https://github.com/SuaveIO/suave/issues/10
PerfUtil PR: https://github.com/eiriktsarpalis/PerfUtil/pull/2

Thinking left: [where do I save the history file](https://github.com/eiriktsarpalis/PerfUtil/issues/1)?