Update announcements.json

announcements.json

 [
+	{"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 (招募开发者/管理员) <-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"},
 	{"id":8,"title":"mycard可以使用Google账号登录了<-戳我查看详情","url":"https://github.com/mycard/mycard/wiki/%E7%94%A8%E6%88%B7", "created_at":"2013-03-25T18:12:07+08:00","updated_at":"2013-03-25T07:12:08+08:00"},