fix(pywifiphisher): fix a bug where ap logo path was used with None
fix(pywifiphisher): fix a bug where ap logo path was used with None

This patch fixes bug #489 where logo path was requsted with a None MAC address. This problem only
occured when user is using the --essid option.

MrMugiwara/wifiphisher,MrMugiwara/wifiphisher