Update announcements.json

announcements.json

 [
-	{"id":13,"title":"对战服务器已经重新开放哦","url":"https://github.com/mycard/mycard/wiki/mycard:%E5%B9%B3%E5%8F%B0%E5%85%B3%E9%97%AD%E5%A3%B0%E6%98%8E","created_at":"2013-07-17T14:34:07+08:00","updated_at":"2013-07-17T14:34:07+08:00"},	
 	{"id":11,"title":"竞赛联盟～暑假赛","url":"http://www.duelcn.com/thread-59737-1-1.html","created_at":"2013-07-15T13:34:07+08:00","updated_at":"2013-07-15T07:12:08+08:00"},	
 	{"id":9,"title":"SD25已更新，戳我查看新卡列表","url":"https://goo.gl/j3V3R","created_at":"2013-06-16T13:34:07+08:00","updated_at":"2013-06-16T07:12:08+08:00"},	
 	{"id":10,"title":"和我签下契约，成为魔法少女吧 (Mycard团队成员招募) <-戳我","url":"https://my-card.in/humans", "created_at":"2013-04-13T18:12:07+08:00","updated_at":"2013-05-30T07:12:08+08:00"},