revamp the way page:treehouse/new works

- treehouse/new is now a regular page, not a special template
- most of the code related to the `new` badge in page:index has been removed
- you're meant to discern between pages you've read vs ones you haven't by looking at the colors of the links (blue vs purple)

template/components/_nav.hbs

@@ -3,17 +3,3 @@
         {{{ include_static 'svg/object/logo.svg' }}}
     </a>
 </nav>
-
-{{!--
-
-I don't have any idea where to put this right now.
-There's no obvious place, and even when it is there, I hate the hideous red badge on new entries.
-No time to figure it out. Will do later.
-
-{{#if (eq page.tree_path 'index')}}
-<nav id="nav-links">
-    <a href="{{ config.site }}/treehouse/new" data-cast="new">new</a>
-</nav>
-{{/if}}
-
---}}