Make share button public

[haiku (Rikki Tooley)]

I did a mock-up

.topic-meta-data .post-info a.post-date:after {
    color: #aaa;
    content: " ";
    font-family: FontAwesome;
}

Worth noting this can be put into any site’s customisation now, untilif it gets into master

Edit: adjusted the CSS so it doesn’t show the icon after the edit pencil.