switch to use Cache.get_multi for tag types

app/models/tag.rb

@@ -102,9 +102,8 @@ class Tag < ActiveRecord::Base
       end
 
       def categories_for(tag_names, options = {})
-        Array(tag_names).inject({}) do |hash, tag_name|
-          hash[tag_name] = category_for(tag_name, options)
-          hash
+        categories = Cache.get_multi(Array(tag_names), "tc") do |tag|
+          Tag.select_category_for(tag)
         end
       end
     end

app/presenters/tag_set_presenter.rb

@@ -68,7 +68,7 @@ class TagSetPresenter < Presenter
   def inline_tag_list(template)
     @tags.map do |tag_name|
       <<-EOS
-        <span class="category-#{Tag.category_for(tag_name)}">
+        <span class="category-#{categories[tag_name]}">
           #{template.link_to(tag_name.tr("_", " "), template.posts_path(tags: tag_name))}
         </span>
       EOS