[DEV-1981] Implement bare AskbotUserAdmin class.
[DEV-1981] Rename fake field methods, add readonly_fields.
[DEV-1981] Re-enable last_seen.
[DEV-1981] Implement link fields for User and Person.
[DEV-1981] Update verbose_names on models for cleaner admin.
Merge pull request #39 from roverdotcom/DEV-1981

[DEV-1981] Create admin interface for AskbotUser.