Scripts will not correctly identify pi-topOS on Stretch

[m-roberts]

Hi,

I am just leaving this here to inform you that the checks currently in place to identify pi-topOS are not going to be valid when we release it for Stretch.

You can, however, check for /etc/pi-top or ~/.config/pi-top directories.

[makermelissa]

Transferring as this is now detected in the get_os() function.