Remove old pygments css and reference in head.html

Issue #1070

Author: samcv

html/css/pygments.css

@@ -2,6 +2,5 @@
 <link rel="icon" href="/favicon.ico" type="image/x-icon" />
 <link type="text/css" href="/css/custom-theme/jquery-ui.css?v=1" rel="stylesheet" />
 <link type="text/css" href="/css/highlights.css?v=5" rel="stylesheet" />
-<link type="text/css" href="/css/pygments.css?v=1" rel="stylesheet" />
 <link rel="stylesheet" type="text/css" href="/css/style.css?v=1" media="screen" title="default" />
 <noscript> <style> #search { visibility: hidden; } </style> </noscript>