Support git code syntax in live preview

Add autocrlf values for Windows, Linux, and OS X.

lib/gollum/frontend/public/gollum/livepreview/js/livepreview.js

@@ -298,6 +298,8 @@ var makePreviewHtml = function () {
   }
 
   var prevTime = new Date().getTime();
+  // Handle gollum file code insertion syntax.
+  text = text.replace(/^[ \t]*``` ?([^:\n\r]+:[^`\n\r]+)```/gm, '``$1``');
   text = md_to_html( text );
 
   // Calculate the processing time of the HTML creation.