This performs purging expired cookies which take up a large portion of HTTP header size, so that it can prevent HTTP 400 Bad Request error caused by exceeding the header length limit. This performs its job automatically (especially on tab active), there is no need of managing or manual clicking, etc.
Changes to 2.0: This removes unnecessary cookies with naming scheme '{GALLERY_ID}_recom_{ARTICLE_ID}'. Those cookie incurs HTTP 400 Bad Request due to header size limit.
