PIN: Replaced AlertDialog with Toast, request PIN 10s after leaving app

- fix #76 
- fix #257 
I wouldn’t say it’s important information. It was annoying before there was no timeout, the timeout is just a fix for it. Not necessary to let people know. We also e.g. don’t say that uploads are retried and such. It’s just backend stuff that needs to work, but doesn’t need to be exposed. :)