Tweak conditions and have Publican build everything
    
    The condition setting in publican.cfg allows us to select what gets
    included.  Unfortunately, if you deselect anything currently, it
    breaks the build.  The right thing to do for now, if you're a remixer
    of this book would probably be just to rewrite the container
    "book.xml" files to keep what you like.
    
    I'm not sure why Publican makes this particular choice, and whether
    it's due to an XML standard or technical requirement.