[fixed] Ignore falsy routes

Routes which are null/undefined should be skipped
in the React.Children traversal when creating routes.
This makes the Router's behavior closer match React
in handling empty elements.

tests/Router-test.js

@@ -832,6 +832,20 @@ describe('Router.run', function () {
     });
   });
 
+  it('does not break on falsy routes', function (done) {
+    var routes = [
+      <Route handler={Foo} path="/foo"/>,
+      null,
+      <Route handler={Bar} path="/bar"/>,
+      undefined
+    ];
+    Router.run(routes, '/foo', function (Handler, state) {
+      var html = React.renderToString(<Handler/>);
+      expect(html).toMatch(/Foo/);
+      done();
+    });
+  });  
+
   it('matches nested routes', function (done) {
     var routes = (
       <Route handler={Nested} path='/'>

utils/createRoutesFromChildren.js

@@ -154,8 +154,8 @@ function createRoutesFromChildren(children, parentRoute, namedRoutes) {
   var routes = [];
 
   React.Children.forEach(children, function (child) {
-    // Exclude <DefaultRoute>s and <NotFoundRoute>s.
-    if (child = createRoute(child, parentRoute, namedRoutes))
+    // Exclude null values, <DefaultRoute>s and <NotFoundRoute>s.
+    if (child && (child = createRoute(child, parentRoute, namedRoutes)))
       routes.push(child);
   });