App crashes if server not available on startup

[lyudmil]

Currently if the server is not running or unreachable, the app will crash when starting up. This is obviously pretty bad. We should, at the very least, fail elegantly. At best, we would provide a way to retry establishing the connection.

[Daedrico]

I'm working on it.
I wish to implement the following checks:
• gps is enable (done)
• internet connection is enable (done)
• server is running (done)

For the first two points: if the check fails, the application shows a dialog box, allowing users to activate gps and/or internet connection.
Last one checks for the machine on which server is reachable; it doesn't really checks if server is running, only if the server machine in online.