disable tag backlinking on posts for anon users (helps with web crawlers)

app/presenters/post_presenter.rb

@@ -22,7 +22,7 @@ class PostPresenter < Presenter
     path = options[:path_prefix] || "/posts"
 
     html =  %{<article itemscope itemtype="http://schema.org/ImageObject" id="post_#{post.id}" class="#{preview_class(post, options[:pool])}" #{data_attributes(post)}>}
-    if options[:tags].present?
+    if options[:tags].present? && !CurrentUser.is_anonymous?
       tag_param = "?tags=#{CGI::escape(options[:tags])}"
     elsif options[:pool_id] || options[:pool]
       tag_param = "?pool_id=#{CGI::escape((options[:pool_id] || options[:pool].id).to_s)}"