title: cordova.plugins undefined for cordova3.1
body: <p>i am trying to develop an android application using cordova. for my application, i require the barcode scanner plugin (<a href="https://github.com/wildabeast/BarcodeScanner/" rel="nofollow">https://github.com/wildabeast/BarcodeScanner/</a>)</p>
  
  <p>i am unable to add the plugin using CLI, so i downloaded and copied the files, added the plugin via the following:</p>
  
  <pre><code>&lt;feature name="BarcodeScanner"&gt;
          &lt;param name="android-package" value="com.phonegap.plugins.barcodescanner.BarcodeScanner" /&gt;
      &lt;/feature&gt;
  </code></pre>
  
  <p>i then added references to the barcodescanner.js and the cordova files in my application. then in my index, i added the following lines of code to read barcode:</p>
  
  <pre><code>var scanner = cordova.plugins.barcodeScanner;
                  scanner.scan(
                      function(result){
                          alert("Scanned Code: " + result.text 
                          + ". Format: " + result.format
                          + ". Cancelled: " + result.cancelled);
                      }, 
                      function(error){
                          alert("Scan failed: " + error);
                      }
                  );
              }
  </code></pre>
  
  <p>but i get the following error:</p>
  
  <pre><code>Uncaught TypeError: Cannot read property 'barcodeScanner' of undefined
  </code></pre>
  
  <p>due to that, i think the cordova.plugins is undefined. what may be the issue for this? am i missing anything?</p>