Button to share on Facebook

`janvitek `
> I was looking at the blog on the PRL web site. It is nice, I should visit it more.
>
> One question: is there a way to add a button to share on Facebook.  I don’t Twit or G+, but I FB.

`o-`
> If anybody starts looking into this, I would suggest to switch to
> something like https://github.com/panzi/SocialSharePrivacy at the same time.
