title: Issue when importing FileTransfer - ionic 3
body: <p>I have installed filetransfer plugin as it mention <a href="https://ionicframework.com/docs/native/file-transfer/" rel="noreferrer">here</a></p>
  
  <p>Here is the code in the app.module.ts:</p>
  
  <pre><code>import { FileTransfer } from '@ionic-native/file-transfer';
  
  providers: [
     ...
     FileTransfer,
     ...
  ]
  </code></pre>
  
  <p>Here is the error</p>
  
  <blockquote>
    <p>Type 'FileTransferOriginal' is not assignable to type 'Provider'.
      Type 'FileTransferOriginal' is missing the following properties from type 'FactoryProvider': provide, useFactoryts(2322)
    (alias) const FileTransfer: FileTransferOriginal
    import FileTransfer</p>
  </blockquote>