remove react-router dependency from breadcrumb

components/breadcrumb/demo/router.md

@@ -35,7 +35,7 @@ var App = React.createClass({
         <Link to="/">首页</Link>
         <Link to="/apps">应用列表</Link>
       </div>
-      <Breadcrumb />
+      <Breadcrumb Router={Router} />
       <RouteHandler />
     </div>);
   }

components/breadcrumb/index.jsx

 'use strict';
 
 import React from 'react';
-import Router from 'react-router';
-
-let Link = Router.Link;
 
 let prefixCls = 'ant-breadcrumb';
 
@@ -24,7 +21,8 @@ let Breadcrumb = React.createClass({
   },
   render() {
     var crumbs, routes, params;
-    if (this.context.router) {
+    if (this.context.router && this.props.Router) {
+      var Link = this.props.Router.Link;
       routes = this.context.router.getCurrentRoutes();
       params = this.context.router.getCurrentParams();
       crumbs = routes.map(function(route, i) {