Second method for WiFi onboarding without Camera

[zytegalaxy]

I think it will be helpful to add a second method WiFi onboarding without Camera; this will be helpful for devices that don't have camera loaded in particular.

There is a common approach that IoT devices use where they become an access point initially and you can connect to them directly to access a local server and pass wifi username/password. After that, wifi stops being an access point and connects as client to the main WiFi. There are some existing libraries for this, but we can do more research on this:

https://github.com/WebThingsIO/gateway-wifi-setup
https://github.com/davidflanagan/wifi-setup
https://github.com/jasbur/RaspiWiFi

cc: @sassanh