[Feature request] Offline status detection and response

[fredvik]

When the OH installation has lost contact with the cloud, there are messages as the app starts up: "Connecting to remote URL" and after a period "Error. The request timed out."

It is not clear from these messages if:
a) the app cannot connect to the myopenhab cloud, or
b) the cloud cannot connect to the OH server

It would be very preferable if messages can be reworded to make it clear which part of the connection has the problem.

When the cloud cannot connect with the server, it would be great to see the date/time of the last successful connection.

[Cossey]

I would also like to add that if I am in the openHAB app and then my Wifi drops out to 3G/4G (for example when I'm leaving my house and go out of range) then the app needs to be closed and re-opened for it to start using the cloud connection. Could this maybe be improved to detect when the network connection changes to cellular and use the cloud connection settings automatically?