Remove the requirement of a U1 account for notifications
Created by: dpniel
The requirement on having a U1 account is purely artificial and not used beyond checking the user actually has an account. This wasn't so much an issue when we only had the canonical store as you needed to sign in to U1 to install apps, but this isn't a requirement with the openstore.
I don't think a user should have to create a U1 account "just" to get notifications when it provides no advantages and isn't actually used by the push service.
This will just require removing the signing-helper
binary and remove the auth checks from the client code.