Accept options object in MqttSecureServer

lib/server.js

@@ -36,21 +36,25 @@ util.inherits(MqttServer, net.Server);
 /**
  * MqttSecureServer
  *
- * @param {String} privateKeyPath
- * @param {String} publicCertPath
+ * @param {Object} opts - server options
  * @param {Function} listener
  */
 var MqttSecureServer = module.exports.MqttSecureServer = 
-function SecureServer(keyPath, certPath, listener) {
+function SecureServer (opts, listener) {
   if (!(this instanceof SecureServer)) {
-    return new SecureServer(listener);
+    return new SecureServer(listener, opts);
   }
+
+  // new MqttSecureServer(function(){})
+  if ('function' === typeof opts) {
+    listener = opts;
+    opts = {};
+  }
+
   var self = this;
 
-  tls.Server.call(self, {
-    key: fs.readFileSync(keyPath),
-    cert: fs.readFileSync(certPath)
-  });
+  tls.Server.call(self, opts);
+
   if (listener) {
     self.on('client', listener);
   }