always include crypto

oauth3.node.js

@@ -10,6 +10,8 @@ var PromiseA = require('bluebird');
 var requestAsync = PromiseA.promisify(require('request'));
 var crypto = require('crypto');
 
+OAUTH3.crypto = OAUTH3.crypto || {};
+OAUTH3.crypto.core = require('./oauth3.node.crypto.js');
 OAUTH3.PromiseA = PromiseA;
 OAUTH3._discoverHelper = function(providerUri, opts) {
   return OAUTH3._node.discover(providerUri, opts);