Get rid of deprecation message

As suggested by nisaacson#16 (not sure why @gubi didn't do it)

lib/raw.js

@@ -3,7 +3,7 @@
  * This module can handle multi-page pdf files
 
  */
-var sys = require('sys');
+var sys = require('util');
 var events = require('events');
 var fs = require('fs');
 var async = require('async');