Better array check in Cert Authority list

lib/crypto.js

@@ -49,7 +49,7 @@ exports.createCredentials = function (options) {
 
   if (options.ca) {
     c.shouldVerify = true;
-    if ( (typeof(options.ca) == 'object') && options.ca.length ) {
+    if (Array.isArray(options.ca)) {
       for (var i = 0, len = options.ca.length; i < len; i++) {
         c.context.addCACert(options.ca[i]);
       }