Send "N comments" links to the comments anchors.

We have to call post.save in the posts/index specs, because post_path
fails unless the post has been persisted (and hence had its slug
generated). I think. That fixed the failing tests, anyway.

app/views/posts/_single.html.haml

@@ -24,7 +24,8 @@
         - unless defined?(hide_comments) 
           .post-comments
             %ul.inline
-              %li.first= link_to pluralize(post.comments.count, "comment"), post
+              %li.first= link_to pluralize(post.comments.count, "comment"),
+                post_path(post, :anchor => 'comments')
               -if can? :create, Comment
                 %li= link_to "Reply", new_comment_path(:post_id => post.id)
               %li= link_to "Permalink", post