fix header levels
ensure that data comes back in utf-8, on MSWin32

e.g.
https://github.com/msysgit/msysgit/wiki/Git-for-Windows-Unicode-Support

http://www.cpantesters.org/cpan/report/0c934f2a-6c17-1014-a945-92c1c8f412ad
http://www.cpantesters.org/cpan/report/0c8fa937-6bf4-1014-9444-f87fab4d9e9f
fix documentation wording (thanks, dagolden!)
start testing the order of the contributor names (currently alphabetical)
add some logging dianostics
create a wrapper sub for git commands, for reducing boilerplate
add "order_by" config, defaulting to "name" (as before)
mark "include_releaser" as experimental and subject to removal