Generalize for any repo

[jericson]

I love the curl dashboard and I want to use some of the stats for other projects. I forked this repository and started generalizing the scripts. For instance, github-cache.pl grabs a copy of issues in any repository. By default it still fetches curl issues. But if you provide another owner/repo, you can get issues from other repositories. Relevant to my interests, OpenSSL:

perl ./stats/github-cache.pl -owner openssl -repo openssl

I've gotten to a point where I'm going to want to remove curl-specific charts. (I love Daniel vs. the rest, but sadly Daniel Stenberg doesn't show up in every GitHub repository.) Before I do that, I was curious if some of my changes would be useful to port back to this repository. If so, I'm happy to work with y'all to make a cleaner patch.