RCX serve - expose interface IP to notification

[0xlne]

As a RCX user, it would be beneficial to expose the interface IP (example 192.168.1.10) in the notification referring to RCX serving instead of the internal one (127.0.0.1). It just makes it easier instead of searching the IP in the Android settings. Alternatively, if RCX is serving to all interfaces, then the notification could be expanded to list the IPs of all physical interfaces (WIFI, GSM).

[x0b]

This should be possible, although the exact implementation details need to be researched. This would also close #59.