Improve github include to indicate issue status

[imagejan]

Similar to how gitter.im renders links to PRs and issues in different colors depending on their status (open/closed), we can consider adding some styling to the {github} inlcude to change the link color (or even show a popup on mouse-over?) dependent on status. It would however involve querying GitHub API for rendering each link.

[ctrueden]

That would be nice indeed. This SO answer provides some guidance on how one would call the GitHub API to get these details from JavaScript.