Update package.json (shakacode#379)

* Update package.json to node 7.8.0 and npm 4.2.0.

Author: justin808

client/package.json

@@ -4,8 +4,8 @@
   "description": "Code from the React Webpack tutorial.",
   "main": "server-express.js",
   "engines": {
-    "node": "7.2.0",
-    "npm": "4.0.2"
+    "node": "7.8.0",
+    "npm": "4.2.0"
   },
   "repository": {
     "type": "git",

package.json

@@ -4,8 +4,8 @@
   "description": "ShakaCode's example of React on Rails plus React Native",
   "main": "server-express.js",
   "engines": {
-    "node": "7.2.0",
-    "npm": "4.0.2"
+    "node": "7.8.0",
+    "npm": "4.2.0"
   },
   "scripts": {
     "postinstall": "cd client && yarn install",