merge duplicated ordered events in events#ordered

  如果对一个活动提交过多个订单，之前会在“参加的活动”页面显示多次。
  本次改动对参加的活动做去重处理。
Merge pull request #558 from Lax/pull_requests/merge_ordered_events

merge duplicated ordered events in events#ordered
Update gemnasium badge link.
merge master.