AP mode IP address

[Neradoc]

In Access Point mode, wifi.radio.ipv4_address is None, instead the IP of the board is wifi.radio.ipv4_address_ap.
In addition both AP and STA modes can be active at the same time.

A minimal change would be to try ipv4_address first, then ipv4_address_ap.
A further addition would be to allow giving the chosen IP address to listen to as an argument to WSGIServer.start and/or always listen to both by default using 0.0.0.0 (if that works, as it seems).

[sabas1080]

the IP default for esp32 in AP mode is 192.168.4.1

[tyeth]

I just stumbled into this, and made the first change without checking issues first 😶‍🌫️ Pull request #10
I like the empty host option(0.0.0.0 default), it works for 192.168.4.1 when I was doing the sockets myself.

I get the impression there will be complications if the user tries to do more than one wifi thing, i.e. start_ap and station/connect too, but the esp32 appears to support it, as the examples include stopping the station first and not calling connect but the comments suggest using both is possible.

My next dream is SSL to get certain browser events unavailable on insecure pages... ah well, baby steps :)