bus factor measure

[sbenthall]

Carrying over some from #10 into a new ticket that reflects the more advanced functionality.

"Given an ordering over participants 1st, 2nd, 3rd most active, and given a distribution of threads involving each participant, it would be nice to have a breakdown f average and max thread size given the conditions that the 1st, (or first and second, or first/second/third) are not participating.

That would be an indication of the project's bus factor.
http://en.wikipedia.org/wiki/Bus_factor"