appeals: only show current appeal on appealed posts.

* Only show the current pending appeal in the "This post was appealed"
  notice. Don't show old appeals.

* Don't show both the "This post was deleted" and the "This post was
  appealed" notice on appealed posts. Only show the "This post was
  appealed" notice.

* Show "no reason" if no appeal reason was given.

app/views/modqueue/_post.html.erb

@@ -68,10 +68,10 @@
         </span>
       <% end %>
 
-      <% if (post.is_flagged? || post.is_deleted?) && post.appeals.any? %>
+      <% if post.is_appealed? %>
         <span class="info">
           <strong>Appeals</strong>
-          <%= render "post_appeals/reasons", appeals: post.appeals %>
+          <%= render "post_appeals/reasons", appeal: post.appeals.select(&:pending?).last %>
         </span>
       <% end %>
     </div>