title: npm install packagename --save-dev not updating package.json
body: <p>Are there simple or subtle reasons that <code>package.json</code> would not update after running a --save-dev? This is my command:</p>
  
  <p><code>npm install modulename --save-dev</code> </p>
  
  <p>Run from the root of the project. The command succeeds, the new module shows up in the node_modules directory as expected. Help would be appreciated. I am using npm v 1.4.28</p>
  
  <p>The entirety of my current <code>package.json</code> is:</p>
  
  <pre><code>{
      "name": "FooWeb",
      "version": "1.0.0",
      "description": "Foo Web",
      "devDependencies": {
          "gulp": "3.8.11",
          "gulp-jshint": "1.9.2",
          "gulp-concat": "2.5.2",
          "gulp-sass": "1.3.3",
          "gulp-sourcemaps": "1.4.0",
          "gulp-watch": "4.1.1"
      }
  }
  </code></pre>
  
  <p>I do get warnings on install of a package that I have no repository field or README, but I think that is not related.</p>