Fix the lost link. (#38)

Author: yusuke

_config.yml

@@ -97,8 +97,8 @@ JB :
   # Some JB helpers refer to these paths; change them here if needed.
   #
   archive_path    : /archive/index.html
-  categories_path : /categories/index.html
-  tags_path       : /tags/index.html
+  categories_path : /packages/category
+  tags_path       : /packages/tag/
   atom_path       : /feed/atom.xml
   rss_path        : /feed/rss.xml