Update announcements.json

announcements.json

 [
+    {"id":29,"title":"平台更新中，暂关服维护。","url":"https://forum.my-card.in/t/mycard-1-4-3","created_at":"2014-09-17T21:00:06+08:00","updated_at":"2014-09-27T21:00:06+08:00"},
     {"id":28,"title":"v1.4.3 更新EP14新卡（10张）","url":"http://fff.ac/9vxuhy","created_at":"2014-09-17T21:00:06+08:00","updated_at":"2014-09-27T21:00:06+08:00"},
     {"id":27,"title":"v1.4.2 补充VB17|15AY新卡（3张）","url":"http://fff.ac/rcz6oi","created_at":"2014-08-25T21:00:06+08:00","updated_at":"2014-09-03T21:00:06+08:00"},
     {"id":26,"title":"v1.4.1 更新BP03|SPRG|T901新卡（45张）","url":"http://fff.ac/4ilyys","created_at":"2014-08-18T17:10:06+08:00","updated_at":"2014-08-28T17:10:06+08:00"},