wifi.sh doesn't kill wpa_supplicant

[jls]

Hi
if wpa_supplicant is running when launching wifi.sh, wifi.sh itself doesn't connect.

[Jason W]

I see dCore has an older version of wifi than Core, and Bela has made some improvements regarding wpa_supplicant so I have updated wifi to Core's current version. 

As I am not very familiar with this utility, and for the ease of keeping up with updates to it made in Core, I don't want to spend time resources on a fork of wifi.sh but rather stick to what Core is using since there are no dCore specific changes needed for it to function.  If the issue you have observed regarding wpa_supplicant does not happen in wifi.sh in Core but does in dCore, then we can pursue a fix to create the expected behavior.  Thanks.