Improve WiFi setup

[mkalkbrenner]

Thanks to @bartdesign, ZeDMD gets a great new WiFi setup process.

As an improvement, ZeDMD should display the SSID and the password and one sentence of explanation on the display if it switches to server mode.

In case of having multiple ZeDMDs, the SSIDs are conflicting. Isuggest to add a random number between 0 and 99 to the SSID.
If we display the SSID, that isn't a problem.