Add support for metadata

address comments

Author: suchitadoshi1987

src/index.js

@@ -27,7 +27,8 @@ function fastbootExpressMiddleware(distPath, options) {
 
   return function(req, res, next) {
     let path = req.url;
-    fastboot.visit(path, { request: req, response: res }).then(success, failure);
+    let visitOptions = Object.assign({}, opts.visitOptions, { request: req, response: res });
+    fastboot.visit(path, visitOptions).then(success, failure);
 
     function success(result) {
       let responseBody = opts.chunkedResponse ? result.chunks() : result.html();