remove dead code

util/util.js

@@ -3,7 +3,6 @@ var crypto = require('crypto');
 var bignum = require('bignum');
 var Binary = require('binary');
 var Put = require('bufferput');
-var Address = require('../Address').class();
 
 var sha256 = exports.sha256 = function (data) {
   return new Buffer(crypto.createHash('sha256').update(data).digest('binary'), 'binary');