Refactor WiFi scan example

[Erriez]

I've refactored the WiFi scan example with better readable output:

ESP8266 WiFi scan example Starting WiFi scan... 10 networks found: 00: [CH 01] [XX:XX:XX:06:4B:E7] -88dBm * V xxxxxxxxxxx 01: [CH 01] [XX:XX:XX:F8:C2:C1] -94dBm * V xxxxxxxxxx 02: [CH 01] [XX:XX:XX:09:6C:21] -89dBm * V xxxxxxx 03: [CH 04] [XX:XX:XX:10:B8:12] -89dBm * V xxxxxxxxxxxxxx 04: [CH 01] [XX:XX:XX:F8:C2:C1] -92dBm * V xxxxxxx 05: [CH 06] [XX:XX:XX:2F:4C:68] -75dBm * V xxxx 06: [CH 01] [XX:XX:XX:09:6C:21] -90dBm * V xxxxxxxxxxxxxx 07: [CH 11] [XX:XX:XX:89:4E:8F] -90dBm * V xxxxxxxxxxxx 08: [CH 11] [XX:XX:XX:34:0E:E0] -69dBm * H 09: [CH 01] [XX:XX:XX:64:AC:1F] -90dBm * V xxxx Starting WiFi scan... ...