payro: fix crypto module require.

lib/PayPro.js

@@ -1,5 +1,7 @@
 'use strict';
 
+var crypto = require('crypto');
+
 var Message = Message || require('./Message');
 
 var RootCerts = require('./common/RootCerts');
@@ -11,7 +13,6 @@ var rfc3280 = require('asn1.js/rfc/3280');
 
 PayPro.prototype.x509Sign = function(key, returnTrust) {
   var self = this;
-  var crypto = require('crypto');
   var pki_type = this.get('pki_type');
   var pki_data = this.get('pki_data');
   pki_data = PayPro.X509Certificates.decode(pki_data);
@@ -56,7 +57,6 @@ PayPro.prototype.x509Sign = function(key, returnTrust) {
 
 PayPro.prototype.x509Verify = function(returnTrust) {
   var self = this;
-  var crypto = require('crypto');
   var pki_type = this.get('pki_type');
   var sig = this.get('signature');
   var pki_data = this.get('pki_data');