Handling of encoding

[melmothx]

It occurred to me that the lines returned by Git::Wrapper are octects, not characters. I understand that this is undertested, given that most of us write commit messages in English/ASCII only, however, looking at the source, it seems that no attempt to decode the strings is done.

This is not a bug per se, but I'd suggest to formalize this in the documentation, so people using the module are aware of what kind of strings to expect.