Implement wifi.setverbose

By default, only errors are logged. By running "wifi.verbose(1)", all
data sent to and received from the wifi module is logged.

Logging only happens to Serial, since it is a bit idea to log data to HQ
(which goes through wifi, causing more log output, causing more traffic,
etc.).
Merge pull request #197 from Pinoccio/wifi.verbose

Implement wifi.setverbose