I wrote a tool like that for Github almost a year ago, finally got around to packaging it. It copies issues, issue events, watched/starred/private/public repos, wikis, etc. All configured via arguments. It's written in python with no external dependencies, so should work fine in most versions:

- https://pypi.python.org/pypi/github-backup

I built it as our company github org is getting quite big, and I wanted to backup my own repositories (at the time I had something like ~300 repos, which I've since slimmed down). Worked well enough for me.