Update counter example: react version to 15.5 (#346)

Author: bossbossk20

examples/counter/components/Counter.js

@@ -1,4 +1,5 @@
-import React, { Component, PropTypes } from 'react';
+import React, { Component } from 'react';
+import PropTypes from 'prop-types';
 import { isMonitorAction } from '../store/configureStore';
 
 class Counter extends Component {

examples/counter/package.json

@@ -17,8 +17,9 @@
   },
   "homepage": "http://rackt.github.io/redux",
   "dependencies": {
-    "react": "^15.1.0",
-    "react-dom": "^15.1.0",
+    "prop-types": "^15.5.8",
+    "react": "^15.5.4",
+    "react-dom": "^15.5.4",
     "react-redux": "^4.4.5",
     "redux": "^3.5.2",
     "redux-devtools-extension": "^1.0.0",