Just to reply on questions about what i did for my N9: I go to Settings > Reset > Clear Device.

This will make you lose all apps and your app data. But changes made to system files still stay. Like changes from N9 QTweak still remains for me.

After the device is done with its stuff, i start to re-install all my usual apps. Lastly, i install Wazapp.

I need to emphasize that this works for me and I am not guaranteeing that this works for you too. But worth a try if you are dying to have Wazapp working, like me... haha