Added author and committer info to parsed repo

- All that is left for the LocalRepoParser::getGitTree() method is to
  get the commit time. I have a method to do so, but the time is
  showing as invalid when setting it via the QDateTime::mSecsFromEpoch
  method.
- Changed all strings returned in LocalRepoParser to QStrings from std
  strings, for consistency and ease. All of the QClasses I was using
  required strings and it didn't make sense to keep converting from
  QString to std::string.