Update sonoff-wifi-switch.groovy

[mattPiratt]

This patch is adding IP address to config panel, because it happened to me that after 2 weeks of using this DTH the IP changed to 0.0.0.0 by itself. It just happened. With this patch, You can set back IP in Device settings in SmartThings App->Things. Otherwise, You would have to add this Device again, and then binding newly added Device with many Routines and SmartApps again.

[steveuk23]

Is this so you can set a static IP through the device settings ? I've recently added a SonoffTH that changes its IP to 0.0.0.0 and I've read someone else who it's also happening to and he's deleted all the code from the smartapp and it's stopped doing it.