Convert HeyPublisher class to Author class

[aguywithanidea]

All of the functions in the HeyPublisher class (/HeyPublisher/HeyPublisher.class.php) deal with creating user objects in WP, or updating user data (like bio) when updates are detected.

This is very old code and not broken - but is in the wrong namespace, now that all class files are in /classes/HeyPublisher and under the HeyPublisher namespace.