Faulty snippet detection on GitHub issues

Created by: chrismwendt

• Visit https://github.com/gorilla/mux/issues/381
• Notice hovers don't work on the first snippet

It looks like this code assumes that the first <a> tag within a comment that links to a URL that can be parsed by getGitHubState(anchor.href) is a snippet, but in that issue it's actually a link to a commit.

One solution is to not stop after the first is found, and to tighten the URL regex.