bugfix?

should solve the following:

```
ActionView::Template::Error (private method `to_ary' called for
#<Comment:0x007fe6ce60e9f8>):
2014-03-12T16:18:29.042229+00:00 app[web.1]:     1: - if
defined?(comments) and comments.first
2014-03-12T16:18:29.042229+00:00 app[web.1]:     2:
#comentario_destacado data-post_id="#{post.slug}"
2014-03-12T16:18:29.042229+00:00 app[web.1]:     3:     = render
comments.first
2014-03-12T16:18:29.042229+00:00 app[web.1]:
app/views/posts/_highlight_comment.html.slim:3:in
`_app_views_posts__highlight_comment_html_slim___4629961319873764_703146
40054220'
2014-03-12T16:18:29.042229+00:00 app[web.1]:
app/views/posts/_post.html.slim:2:in
`_app_views_posts__post_html_slim___1325819212613284967_70314639897480'
2014-03-12T16:18:29.042229+00:00 app[web.1]:
app/views/home/index.html.slim:1:in
`_app_views_home_index_html_slim__4063193396033533271_70314639743140'
```