Pods object for users doesn't include last_name or first_name pods::import can not import data to these fields.

User in [this thread](http://pods.io/forums/topic/inserting-users-with-pods-object-and-import-method/) reports that they can't get pods::import to import to the first_name and last_name fields in a Pods extended users table.

They also report and I can confirm (using WP 3.8 beta and Pods 2.3.18) that the Pods object does not contain these fields.
