http_* metrics

[errordeveloper]

It seems like the metrics exposed right now do not adhere to best-practice. I'd like to discuss this before proposing any changes :)

[errordeveloper]

Ok, just reviewed my findings from earlier on, and I think the only odd thing is the unit of time – some of my colleagues insist that _seconds should be used instead of _miliseconds, but I don't think there is an agreement on this in the wider community... Let's discuss, may be we could make the unit configurable?

[errordeveloper]

@tcolgate @Olical renamed this to *_seconds in their fork.

[roylines]

Happy to take a pull request on this. Please follow these guidelines if you do