re: #119 book reader

* themes/v3/views/attachments/_display-media.html.erb
  ** changed the logic so that the book reader test uses attachments.size
  ** moved the book reader logic so that the iframe is placed within the <li/>

* public/themes/v3/stylesheets/all.css
  ** added a thin line between the main carousel and thumbnail sections so we can distinguish between for now. can be taken out later if necessary.