Don't load an external stylesheet in 404 page

Before this commit the non-built css as well as an external css page
from the ghost project would be loaded on the 404 page. We should load
the same local css as the rest of the pages.

Author: mattdangerw

404.html

@@ -17,8 +17,8 @@
     <title>{{ page.title }}</title>
     <meta name="HandheldFriendly" content="True" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-    <link rel="stylesheet" type="text/css" href="{{ site.baseurl }}assets/css/screen.css" />
-    <link rel="stylesheet" type="text/css" href="https://demo.ghost.io/assets/built/screen.css?v=724281a32e" />
+    <link rel="stylesheet" type="text/css" href="{{ site.baseurl }}assets/built/screen.css" />
+    <link rel="stylesheet" type="text/css" href="{{ site.baseurl }}assets/built/screen.edited.css" />
     <!-- This tag outputs SEO meta+structured data and other important settings -->
     {% include head.html %}
 </head>