fix tests for kdf

test/crypto/kdf.js

@@ -1,6 +1,9 @@
+'use strict';
+
 var should = require('chai').should();
-var KDF = require('../lib/kdf');
+var bitcore = require('bitcore');
-var Hash = require('../lib/hash');
+var KDF = bitcore.KDF;
+var Hash = bitcore.Hash;
 
 describe('KDF', function() {