Prettify authors

So I've noticed that bones_get_the_author_posts_link() exclusively returns the username when I would argue the desired behavior is to return the nickname if it's set. That enables you to give authors their own formal pen name and display that while keeping the first name and last name fields usable for internal purposes and not public in case you want to use an alias for the nick. The fallback is to simply return get_the_author() like bones has before.