Display latest version & download link from GitHub releases

[strogonoff]

We don’t want to have to manually update project & hub sites each time a new software package version gets released. We can get that information automatically. It’s not possible to get versions from native Git repo information (tags aren’t reliable), but we can use hosting APIs for that.

It does not imply lock-in to GitHub as it’s also possible with Gitlab Releases and Bitbucket Versions. GitHub makes for a great first integration though as it’s used for Ribose projects internally.