added favicon

_layouts/default.html

@@ -12,7 +12,7 @@
   <link rel="canonical" href="{{ site.url }}{{ page.url | replace:'index.html','' }}" />
 
   <link href="//fonts.googleapis.com/css?family=Open+Sans:600,800" rel="stylesheet" type="text/css">
-  <link rel="shortcut icon" href="/favicon.png">
+  <link rel="shortcut icon" href="/favicon.ico">
   <link rel="alternate" type="application/rss+xml" title="{{ site.theme.name }}" href="{{site.url}}/atom.xml" />
 
   <link rel="stylesheet" href="/css/font-awesome.css">