Update whatsprot.class.php

Hi @mgp25 , 
please you must consider that more and mooooooore senders already registered from old WhatsAPI and WART , so that please accent this updates to enable these senders to be controled and managed easily .
I added condition to use the same Identity if it is generated from WhatsAPI or WART and use the new Identity is user registered it from your new API .

Thanks