Allow user to connect to 'favorite' Gateways

[kevinmershon]

Currently, the app is hard-coded to connect to a gateway at 192.168.1.10 port 5094.

Add on the navigation menu and dashboard an option to get to a screen for defining a list of Gateways. If no favorites have been created, default to having one entry for the current hard-coded Gateway information. Allow the user to enter any number of Gateways, having fields Name (default wihartgw), IP (default 192.168.1.10), and Port (default 5094). Gateways can be deleted from the list. Do not allow the user to delete the last Gateway if there is only one remaining. IP address and port text entry should be sensibly restrictive so the IP is numeric with each set between 0 and 255, and the port is between 0 and 65535.

The application will henceforth need to start by prompting the user which Gateway to connect to as a dialog or something equivalent. The app can only be connected to one Gateway at a time. All data recorded (device count, transmitter list, hart variables, and network statistics) should be attributed to the Gateway so data is not mixed up or corrupted.