Start implementing post info at bottom

Now, all posts show info about: author, updated date, tags.
However, styling is needed and also the tags part has to be fixed (we need to add a comma after every tag's name, excluding the last one)

partials/post-card-small.hbs

@@ -12,8 +12,8 @@
                 <header class="mind-post-card-sidebar_header">
                     <p class="mind-post-card-sidebar_meta"><span
                             class="mind-post-card-sidebar_tag">{{primary_tag.name}}</span> •
-                        <time class="post-date" datetime="{{date format='YYYY-MM-DD'}}">{{date
-                                format="DD MMMM YYYY"}}</time>
+                        <time class="post-date" datetime="{{date published_at format='YYYY-MM-DD'}}">{{date
+                                published_at format="DD MMMM YYYY"}}</time>
                     </p>
                     <h5>{{title}}</h5>
                 </header>