use user.is_spam flag instead of virtual is_spammer attribute

[aka47]

In apex only a virtual is_spammer is used that relies on users..flags information. But we are mainly using the user.is_spam flag determines if a user is spam or not - in the mothership.

That did cause async states, where a user's comments were not shown because he had a spam flag. But the mothership send out a notification because user.is_spam was false. So lets use the same information in apex.