多電視同步歷史與進度

[bobyang3]

抱歉. 發現上次因爲修forked dev造成 0 files PR. 再次申請PR. 這是第一個完成的主機選項，之後有Gist sync, google sync, samba sync, webdav sync等計劃，可能還加入同步 keep

NOTE: 因爲DB改變，需要先反安裝舊版本再安裝才會有新的資料庫欄位，才不會有app壞掉無法啓動訊息

Sync History and watched length between devices by using FTP:

1. Add two more fields, deleted (bool) and lastupdated in DB (datetime in UTC so people can sync if they need to go to a different timezone for a trip)
2. Use Soft deletion instead of Hard deletion. And design to hard delete after xx days when there is no more devices to sync. The reason is that, we need a way to identify if the history record is removed or a new inserted across multiple TVs. keep the row to identify new records or has been deleted.
3. FTP will crate folders automatically if folders are missing
4. Sync will run when the app starts or when the user clicks on "Sync" button in Settings.