title: npm install command doing nothing
body: <p>I have a package.json with the following contents:</p>
  
  <pre><code>{
    "name": "useless-app",
    "version": "1.0.0",
    "dependencies": {},
    "devDependencies": {
      "grunt": "~0.4.1",
      "grunt-contrib-copy": "~0.4.0",
      "grunt-contrib-concat": "~0.2.0",
      "grunt-contrib-coffee": "~0.6.6",
      "grunt-contrib-jst": "~0.5.0",
      "grunt-contrib-uglify": "~0.2.0",
      "grunt-contrib-compass": "~0.2.0",
      "grunt-contrib-jshint": "~0.4.3",
      "grunt-contrib-cssmin": "~0.6.0",
      "grunt-contrib-connect": "0.3.0",
      "grunt-contrib-clean": "0.4.0",
      "grunt-contrib-htmlmin": "0.1.3",
      "grunt-contrib-imagemin": "0.1.4",
      "grunt-contrib-livereload": "0.1.2",
      "grunt-mocha": "~0.3.1",
      "grunt-bower-requirejs": "~0.4.1",
      "grunt-usemin": "~0.1.10",
      "grunt-requirejs": "~0.3.5",
      "grunt-regarde": "~0.1.1",
      "grunt-open": "~0.2.0",
      "matchdep": "~0.1.2"
    },
    "engines": {
      "node": "&gt;=0.8.0"
    }
  }
  </code></pre>
  
  <p>Which is what Yeoman built for me as standard. When I call <code>npm install</code> or <code>npm install -g</code> I get no action, just this:</p>
  
  <pre><code>Alex@iMac-2 ~/Sites/Backbone/Yeoman$ sudo npm install -g
  useless-app@1.0.0 /usr/local/lib/node_modules/useless-app
  </code></pre>
  
  <p>At this point I was somewhat expecting a list of applications being downloaded and installed. Either way, testing this by running grunt (one of the items from the list), results in the following:</p>
  
  <pre><code>Alex@iMac-2 ~/Sites/Backbone/Yeoman$ grunt
  -bash: grunt: command not found
  </code></pre>
  
  <p>Any ideas why these things aren't installing?</p>
  
  <p>I have tried using <code>sudo</code> for these commands and the result is always the same.</p>