title: cannot use cordova plugin to open files under ionic 2 and typescript
body: <p>I am developing an android app based on <strong>ionic 2</strong> using <strong>typescript</strong>.
  I would like o open a PDF file inside my app with another app that is registered for the fyletype (e.g. Acrobat Reader).
  Therefore i tried the two standard plugins:</p>
  
  <p><a href="https://github.com/disusered/cordova-open" rel="nofollow">https://github.com/disusered/cordova-open</a>
  <a href="https://github.com/pwlin/cordova-plugin-file-opener2" rel="nofollow">https://github.com/pwlin/cordova-plugin-file-opener2</a></p>
  
  <p>Although ive added both plugins via "ionic plugin add ..." and of course played around with several combination referencing to it 
  the result is always that they ere not found</p>
  
  <p><strong>cordova-open</strong></p>
  
  <pre><code>var open = cordova.plugins.disusered.open;
  </code></pre>
  
  <p>Property 'disusered' does not exist on type 'CordovaPlugins'.</p>
  
  <p><strong>cordova-plugin-file-opener2</strong></p>
  
  <pre><code>cordova.plugins.fileOpener2.open(
      filePath, 
      fileMIMEType, 
      {
          error : function(){ }, 
          success : function(){ } 
      } 
  );
  </code></pre>
  
  <p>Property 'fileOpener2' does not exist on type 'CordovaPlugins'.</p>
  
  <p>I am running the app on an emulator via <strong>ionic run android</strong></p>
  
  <p>Could you please give some hint how i can achieve to use one of these plugins?
  Thank you very much</p>
  
  <p>Shane</p>