Send notification to maintainers when the server is unreachable

[Gerzer]

Currently, we display an error message to the user whenever they open the app and the app detects that the server is unreachable. We should add some code that automatically sends a notification to us, the maintainers, whenever this occurs. Since we obviously can’t use our own server for this, we should look into third-party services that can accept an HTTP request and notify us upon receipt of that request in a timely manner.