use path option instead of root

lib/server.js

@@ -212,7 +212,7 @@ PeerServer.prototype._initializeHTTP = function() {
 
   this._app.on('MethodNotAllowed', unknownMethodHandler);
 
-  this._app.get('/', function(req, res, next) {
+  this._app.get(this._options.path, function(req, res, next) {
     res.send(require('../app.json'));
   });