Comment 2 for bug 880207

I'm looking at the patch now. Could we make the formatter API backward-
compatible by putting the 'n_skipped' argument last, and defaulting it to
'None'? I realize that it makes the API read somewhat awkwardly, but I
think that having things "Just Work" under older Python versions, or where
'unittest2' is not present, trumps that. We could then keep the output text
compatible if 'n_skipped' was not passed (those same cases).