Implemented a version check of npm to give a soft tip during the inst…

…all procedure

and fixed gitignore

.gitignore

@@ -1,3 +1,4 @@
+.vscode/
 node_modules/
 build
 .DS_Store

packages/create-react-app/index.js

@@ -121,6 +121,21 @@ function createApp(name, verbose, version, template) {
   );
   console.log();
 
+  // Check npm version
+  var npmVersionProc = spawn.sync('npm', ['--version']),
+      npmVersion = npmVersionProc.stdout;
+  if (npmVersion) {
+    var recommendVersion = semver.lt(npmVersion.toString(), '3.0.0');
+    if (recommendVersion) {
+      console.log(
+        chalk.green(
+          'Tip: It looks like you are using npm 2.\n' + 
+          'We suggest using npm 3 or Yarn for faster install times and less disk space usage.'
+        )
+      );
+    }
+  }
+
   var packageJson = {
     name: appName,
     version: '0.1.0',

packages/react-scripts/package.json

@@ -72,4 +72,4 @@
   "optionalDependencies": {
     "fsevents": "1.0.17"
   }
-}
+}