It's impossible that whatsapp blocked wazapp for registration
How do you guys think they can do this?
Blocking IMEI? Then why it works in NITDroid?
Wazapp uses symbian agent for registration.
I've updated it in my source.

tgalal seems to be on vacations or something, cause I can't commit to his repo anymore and I can't contact him.

But you can try downloading and compiling it from here:
https://github.com/CepiPerez/wazapp
I've fixed some issues, you can compile wazapp using qtcreator now